Deshab-OS/CODE/dsk/main.c

/* DSK Main Kernel — boot entry, FAT32 firstInit check, ELF loader */

#include "../UTSM/include/utsm/dsk.h"
#include "port.h"

/* Embedded Logo.png RGBA data (auto-generated by png_to_rgba.py) */
#include "logo_data.c"

/* Embedded ASCII bitmap font (Consolas 18px grayscale, 11x18 cell) */
#include "../firstInit/ascii_bitmaps.c"

#define COM1 0x3F8

typedef unsigned char      u8;
typedef unsigned short     u16;
typedef unsigned int       u32;
typedef unsigned long long u64;
typedef long long          i64;

typedef int (*block_read_fn)(u32 index, u64 lba, u32 count, void *buf);
typedef int (*block_write_fn)(u32 index, u64 lba, u32 count, const void *buf);

/* freestanding 无 stddef.h，本地提供 offsetof */
#ifndef offsetof
#define offsetof(type, member) __builtin_offsetof(type, member)
#endif

/* ---- BUG-021 修复: kernel_api 镜像结构体 + 编译期偏移校验 ----
 * DSK 独立编译不含 dkm_kernel_api 定义，为避免硬偏移脆蠕性，
 * 在此定义镜像结构体并用 _Static_assert 校验 block 字段偏移
 * 与 dkm.h 中 dkm_kernel_api.block (0xA8) 一致。 */
typedef struct dsk_block_api_mirror {
    void *pad0; void *pad1;  /* register_device, device_count */
    block_read_fn  read;
    block_write_fn write;
} dsk_block_api_mirror;

typedef struct dsk_kernel_api_mirror {
    u32 version; u32 size; u64 feature_bits;
    const void *log; const void *mem; const void *utsm;
    const void *irq; const void *pci; const void *dma;
    const void *vfs; const void *net; const void *timer; const void *drr;
    const void *rsdp_address; const void *fb_address;
    u64 fb_width; u64 fb_height; u64 fb_pitch; u16 fb_bpp; u16 _pad_bpp;
    const void *boot_modules_response;
    int (*irq_register)(u8 irq, void *handler);
    u64 hhdm_offset;
    const dsk_block_api_mirror *block;   /* 必须在偏移 0xA8 */
    const void *mmio;
    void *(*mm_map_mmio)(u64 phys, u64 size);
    void (*mm_unmap_mmio)(void *virt, u64 size);
} dsk_kernel_api_mirror;
_Static_assert(offsetof(dsk_kernel_api_mirror, block) == 0xA8,
    "dsk_kernel_api_mirror.block offset must be 0xA8 (matching dkm_kernel_api)");
_Static_assert(offsetof(dsk_block_api_mirror, read) == 16,
    "dsk_block_api_mirror.read offset must be 16 (matching dkm_block_api)");

static void sputc(char c) { for(unsigned i=0;i<100000;i++){if(inb(COM1+5)&0x20)break;} outb(COM1,(u8)c); }
static void swrite(const char *s) { while(*s){if(*s=='\n')sputc('\r');sputc(*s++);} }
static void logl(const char *s) { swrite(s); swrite("\n"); }
static void logh(const char *p, u64 v) { static const char h[]="0123456789abcdef"; char b[19]; int i=0; b[i++]='0';b[i++]='x';
  for(int j=15;j>=0;j--)b[i++]=h[(v>>(j*4))&0xf];b[i]=0; swrite(p);swrite(b);swrite("\n"); }

/* ---- DSK 插桩: 轻量级 TSC 计时 (forward-declared, rdtsc_dsk defined later) ---- */
static u64 rdtsc_dsk(void);
#define DSK_TS_DECL(name) static u64 name##_ts = 0
#define DSK_TS_BEGIN(name) do { name##_ts = rdtsc_dsk(); } while(0)
#define DSK_TS_END(name, label) do { \
    if (g_tsc_per_ms) { \
        u64 _d = rdtsc_dsk() - name##_ts; \
        u64 _ms = _d / g_tsc_per_ms; \
        logl("[DSK:TS] " label); logh(" elapsed_ms=", _ms); \
    } \
} while(0)

/* ---- DSK 插桩: 操作计数器 ---- */
#define DSK_STAT_DECL(name) static u32 name##_count = 0
#define DSK_STAT_INC(name) do { name##_count++; } while(0)

static void *memset_dsk(void *d, int c, u64 n) { u8 *p=(u8*)d; while(n--)*p++=(u8)c; return d; }
static void *memcpy_dsk(void *d, const void *s, u64 n) { u8 *dd=(u8*)d; const u8 *ss=(const u8*)s; while(n--)*dd++=*ss++; return d; }

typedef struct __attribute__((packed)) {
    u8 jmp[3]; char oem[8]; u16 bps; u8 spc; u16 rsvd; u8 fc; u16 root_ent;
    u16 ts16; u8 media; u16 spf16; u16 spt; u16 heads; u32 hidden; u32 ts32;
    u32 spf; u16 flags; u16 ver; u32 root_clus; u16 fsi; u16 bkboot;
    u8 res[12]; u8 drv; u8 ntfl; u8 sig; u32 ser; char lbl[11]; char typ[8];
    u8 code[420]; u16 boot_sig;
} fat32_bpb;

typedef struct __attribute__((packed)) {
    char name[11]; u8 attr; u8 ntr; u8 ctenth;
    u16 ctime; u16 cdate; u16 adate; u16 chigh;
    u16 wtime; u16 wdate; u16 clow; u32 fsize;
} fat32_de;

static u32 r32(const u8 *p) { return (u32)p[0]|((u32)p[1]<<8)|((u32)p[2]<<16)|((u32)p[3]<<24); }
static u16 r16(const u8 *p) { return (u16)p[0]|((u16)p[1]<<8); }
static int neq11(const char *a, const char *b) { for(int i=0;i<11;i++) if(a[i]!=b[i]) return 0; return 1; }

static u64 g_fb_addr, g_fb_w, g_fb_h, g_fb_p;
static block_read_fn g_block_read;
static block_write_fn g_block_write;
static u64 g_tsc_per_ms = 0;
static u8 g_disk[131072];
static u8 g_cluster[4096];
static u8 g_fdata[2097152]; /* 2MB file data buffer (与 UTSM 端一致) */
/* BUG-019 修复: FAT 按需扇区读取缓冲区（仅 512 字节） */
static u8 g_fat_sec[512];
static u8 g_milestone_buf[4096]; /* milestone write cluster buffer */

DSK_STAT_DECL(fat32_read);
DSK_STAT_DECL(fat32_write);
DSK_STAT_DECL(elf_load);
DSK_STAT_DECL(mod_schedule);

static int fat32_read_sectors(u32 lba, u32 count, u8 *out) { DSK_STAT_INC(fat32_read); return g_block_read ? g_block_read(0,lba,count,out) : -1; }
static int fat32_write_sectors(u32 lba, u32 count, const u8 *buf) { DSK_STAT_INC(fat32_write); return g_block_write ? g_block_write(0,lba,count,buf) : -1; }

/* BUG-019 修复: 按需读取 FAT 扇区获取下一个簇号。
 * 如果 FAT 条目在预读缓冲区内直接读取；
 * 否则只读取包含该条目的单个 FAT 扇区（512 字节）。 */
static u32 fat32_get_next_cluster(u32 fat_byte_off, u32 clus, u32 fat_rsvd_sec) {
    u32 ent_off = fat_byte_off + clus * 4;
    /* 情况 1: 在预读缓冲区内 */
    if (ent_off + 4 <= sizeof(g_disk)) {
        return r32(g_disk + ent_off) & 0x0FFFFFFF;
    }
    /* 情况 2: 超出预读缓冲区——按需读取单扇区 */
    u32 fat_byte_in_fat = clus * 4;
    u32 sec_idx = fat_byte_in_fat / 512;
    u32 off_in_sec = fat_byte_in_fat % 512;
    u32 sec_lba = fat_rsvd_sec + sec_idx;
    if (fat32_read_sectors(sec_lba, 1, g_fat_sec) != 0) {
        logl("[DSK] FAT32: on-demand FAT sector read failed");
        logh("[DSK] FAT32: sec_lba=", (u64)sec_lba);
        return 0x0FFFFFFF;
    }
    return r32(g_fat_sec + off_in_sec) & 0x0FFFFFFF;
}

/* ---- DSK 内嵌 INI 解析器 ---- */
typedef struct { char section[32]; char key[32]; char value[64]; } dsk_ini_entry;
typedef struct { dsk_ini_entry entries[64]; u32 count; } dsk_ini_config;

static int dsk_ini_streq(const char *a, const char *b) {
    if(!a||!b) return 0;
    while(*a&&*b){ if(*a!=*b) return 0; a++; b++; }
    return *a==*b;
}

static int dsk_ini_atoi(const char *s) {
    int neg=0, v=0;
    if(!s) return 0;
    while(*s==' '||*s=='\t') s++;
    if(*s=='-'){neg=1;s++;}
    while(*s>='0'&&*s<='9'){v=v*10+(*s-'0');s++;}
    return neg?-v:v;
}

static int dsk_ini_parse_bool(const char *s) {
    if(!s) return -1;
    if(s[0]=='1') return 1;
    if(s[0]=='0') return 0;
    if(dsk_ini_streq(s,"true"))  return 1;
    if(dsk_ini_streq(s,"false")) return 0;
    return -1;
}

static int dsk_ini_parse(const char *text, u32 size, dsk_ini_config *cfg) {
    if(!text||!cfg) return -1;
    cfg->count = 0;
    char cur_sec[32]; for(int i=0;i<32;i++) cur_sec[i]=0;
    u32 pos = 0;
    while(pos < size) {
        while(pos<size&&(text[pos]==' '||text[pos]=='\t')) pos++;
        if(pos>=size) break;
        char c = text[pos];
        if(c=='\n'){pos++;continue;}
        if(c=='#'||c==';'){while(pos<size&&text[pos]!='\n')pos++;continue;}
        if(c=='['){
            pos++;
            u32 si=0;
            while(pos<size&&text[pos]!=']'&&text[pos]!='\n'&&si+1<32) cur_sec[si++]=text[pos++];
            cur_sec[si]=0;
            while(pos<size&&text[pos]!='\n') pos++;
            continue;
        }
        if(cfg->count>=64) break;
        dsk_ini_entry *e = &cfg->entries[cfg->count];
        u32 ki=0;
        while(pos<size&&text[pos]!='='&&text[pos]!='\n'&&!(text[pos]==' '||text[pos]=='\t')&&ki+1<32) e->key[ki++]=text[pos++];
        e->key[ki]=0;
        while(pos<size&&(text[pos]==' '||text[pos]=='\t')&&text[pos]!='\n') pos++;
        if(pos>=size||text[pos]!='='){while(pos<size&&text[pos]!='\n')pos++;continue;}
        pos++;
        while(pos<size&&(text[pos]==' '||text[pos]=='\t')&&text[pos]!='\n') pos++;
        u32 vi=0;
        while(pos<size&&text[pos]!='\n'&&vi+1<64) e->value[vi++]=text[pos++];
        while(vi>0&&(e->value[vi-1]==' '||e->value[vi-1]=='\t')) vi--;
        e->value[vi]=0;
        for(int i=0;i<32;i++) e->section[i]=cur_sec[i];
        cfg->count++;
    }
    return 0;
}

static const char *dsk_ini_get(const dsk_ini_config *cfg, const char *sec, const char *key) {
    if(!cfg||!sec||!key) return 0;
    for(u32 i=0;i<cfg->count;i++)
        if(dsk_ini_streq(cfg->entries[i].section,sec)&&dsk_ini_streq(cfg->entries[i].key,key))
            return cfg->entries[i].value;
    return 0;
}

__attribute__((unused))
static int dsk_ini_get_int(const dsk_ini_config *cfg, const char *sec, const char *key, int def) {
    const char *v=dsk_ini_get(cfg,sec,key);
    if(!v||v[0]==0) return def;
    return dsk_ini_atoi(v);
}

static int dsk_ini_get_bool(const dsk_ini_config *cfg, const char *sec, const char *key, int def) {
    const char *v=dsk_ini_get(cfg,sec,key);
    if(!v||v[0]==0) return def;
    int b=dsk_ini_parse_bool(v);
    return (b>=0)?b:def;
}

/* ---- DSK FAT32 子目录遍历 ---- */

/* 在指定起始 cluster 的目录中查找 name11。
 * is_dir=1 只匹配子目录，is_dir=0 只匹配文件。
 * 注意：需先调用 fat32_read_sectors(0,256,g_disk) 确保 BPB 缓冲可用。 */
static int fat32_find_in_dir(u32 start_clus, const char *name11, int is_dir, u32 *out_clus, u32 *out_size) {
    const fat32_bpb *bpb = (const fat32_bpb *)g_disk;
    if(bpb->boot_sig!=0xAA55||bpb->bps!=512) return -2;
    u32 data_lba = bpb->rsvd + (u32)bpb->fc * bpb->spf;
    u32 fat_byte_off = bpb->rsvd * 512;
    u32 spc = bpb->spc;

    u32 clus = start_clus;
    while(clus>=2 && clus<0x0FFFFFF8) {
        u32 lba = data_lba + (clus-2)*spc;
        const u8 *cb;
        if((u64)lba*512+(u64)spc*512<=256ULL*512)
            cb = g_disk + (u64)lba*512;
        else {
            if(fat32_read_sectors(lba,8,g_cluster)!=0) return -3;
            cb = g_cluster;
        }
        const fat32_de *dir = (const fat32_de *)cb;
        for(u32 e=0; e*32<spc*512; e++) {
            if(dir[e].name[0]==0) break;
            if((u8)dir[e].name[0]==0xE5) continue;
            if(dir[e].attr==0x0F) continue;
            if(dir[e].attr&0x08) continue;
            if(!neq11(dir[e].name,name11)) continue;
            int entry_is_dir = (dir[e].attr&0x10)?1:0;
            if(entry_is_dir!=is_dir) continue;
            *out_clus = r16((const u8*)&dir[e].clow)|((u32)r16((const u8*)&dir[e].chigh)<<16);
            *out_size = dir[e].fsize;
            return 0;
        }
        /* BUG-019: 使用按需 FAT 读取 */
        clus = fat32_get_next_cluster(fat_byte_off, clus, bpb->rsvd);
    }
    return -4;
}

/* 按 '/' 分隔的 8.3 路径读取文件（如 "SYSTEM  /DESHAB64 /FUCK    "）。
 * 需先调用 fat32_read_sectors(0,256,g_disk) 确保 BPB 可用。 */
static int fat32_read_path(const char *path, u8 **out_data, u32 *out_size) {
    DSK_TS_DECL(fat32_path_read);
    DSK_TS_BEGIN(fat32_path_read);
    const fat32_bpb *bpb = (const fat32_bpb *)g_disk;
    if(bpb->boot_sig!=0xAA55||bpb->bps!=512) { logl("[DSK] fat32_read_path: bad BPB"); return -2; }
    u32 fat_byte_off = bpb->rsvd*512;
    u32 data_lba = bpb->rsvd + (u32)bpb->fc*bpb->spf;
    u32 spc = bpb->spc;

    u32 pos=0, path_len=0;
    while(path[path_len]) path_len++;
    u32 cur_clus = bpb->root_clus;

    while(pos<path_len) {
        char comp[12]; u32 ci=0;
        while(pos<path_len&&path[pos]!='/'&&ci<11) comp[ci++]=path[pos++];
        while(ci<11) comp[ci++]=' ';
        comp[11]=0;
        if(pos<path_len&&path[pos]=='/') pos++;
        int is_last = (pos>=path_len);

        if(is_last) {
            u32 found_clus=0, found_size=0;
            if(fat32_find_in_dir(cur_clus,comp,0,&found_clus,&found_size)!=0) { logl("[DSK] fat32_read_path: file not found: "); swrite(path); swrite("\n"); return -4; }
            if(found_size>sizeof(g_fdata)) { logh("[DSK] fat32_read_path: file too large size=", (u64)found_size); return -5; }
            u8 *dst=g_fdata; u32 remaining=found_size; u32 fc=found_clus;
            while(fc>=2&&fc<0x0FFFFFF8&&remaining>0) {
                u32 fc_lba=data_lba+(fc-2)*spc;
                u32 fc_bytes=spc*512;
                if(fc_bytes>remaining) fc_bytes=remaining;
                const u8 *fb;
                if((u64)fc_lba*512+(u64)spc*512<=256ULL*512)
                    fb=g_disk+(u64)fc_lba*512;
                else {
                    if(fat32_read_sectors(fc_lba,8,g_cluster)!=0) { logh("[DSK] fat32_read_path: data cluster read failed lba=", (u64)fc_lba); return -6; }
                    fb=g_cluster;
                }
                for(u32 b=0;b<fc_bytes;b++) dst[b]=fb[b];
                dst+=fc_bytes; remaining-=fc_bytes;
                /* BUG-019: 使用按需 FAT 读取 */
                fc = fat32_get_next_cluster(fat_byte_off, fc, bpb->rsvd);
            }
            *out_data=g_fdata; *out_size=found_size;
            DSK_TS_END(fat32_path_read, "fat32_read_path");
            return 0;
        } else {
            u32 sub_clus=0, sub_size=0;
            if(fat32_find_in_dir(cur_clus,comp,1,&sub_clus,&sub_size)!=0) { logl("[DSK] fat32_read_path: dir not found in path: "); swrite(path); swrite("\n"); return -7; }
            cur_clus=sub_clus;
        }
    }
    DSK_TS_END(fat32_path_read, "fat32_read_path (failed)");
    return -8;
}

/* Navigate a '/'-separated 8.3 path to find a directory cluster.
 * Returns the cluster of the final directory, or 0 on failure.
 * Requires g_disk to contain a valid BPB. */
static u32 fat32_find_dir_cluster(const char *path) {
    const fat32_bpb *bpb = (const fat32_bpb *)g_disk;
    if (bpb->boot_sig != 0xAA55 || bpb->bps != 512) return 0;
    u32 pos = 0, path_len = 0;
    while (path[path_len]) path_len++;
    u32 cur_clus = bpb->root_clus;
    while (pos < path_len) {
        char comp[12]; u32 ci = 0;
        while (pos < path_len && path[pos] != '/' && ci < 11) comp[ci++] = path[pos++];
        while (ci < 11) comp[ci++] = ' ';
        comp[11] = 0;
        if (pos < path_len && path[pos] == '/') pos++;
        u32 sub_clus = 0, sub_size = 0;
        if (fat32_find_in_dir(cur_clus, comp, 1, &sub_clus, &sub_size) != 0) return 0;
        cur_clus = sub_clus;
    }
    return cur_clus;
}

#define EI_MAG0 0x7f
#define ELFCLASS64 2
#define ELFDATA2LSB 1
#define EM_X86_64 62
#define PT_LOAD 1
#define PT_DYNAMIC 2
#define DT_RELA 7
#define DT_RELASZ 8
#define DT_RELAENT 9
#define R_X86_64_RELATIVE 8
typedef struct { u8 ident[16]; u16 type,machine; u32 ver; u64 entry,phoff,shoff; u32 flags; u16 ehsize,phentsize,phnum,shentsize,shnum,shstrndx; } elf64_ehdr;
typedef struct { u32 type,flags; u64 offset,vaddr,paddr,filesz,memsz,align; } elf64_phdr;
typedef struct { i64 tag; u64 val; } elf64_dyn;
typedef struct { u64 offset; u64 info; i64 addend; } elf64_rela;

#define BG_TOP    0xFFC8E0F0u
#define BG_BOTTOM 0xFF49306Fu
#define BG_MID    0xFF8888B0u

/* ---- TSC-based timing ---- */
static u64 rdtsc_dsk(void) {
    u32 lo, hi;
    __asm__ volatile("rdtsc" : "=a"(lo), "=d"(hi));
    return ((u64)hi << 32) | lo;
}

static void tsc_calibrate_dsk(void) {
    outb(0x43, 0x30);       /* ch0, lo+hi, mode 0, binary */
    outb(0x40, 0x7c);       /* 11932 low = ~10ms */
    outb(0x40, 0x2e);       /* 11932 high */
    u64 tsc_start = rdtsc_dsk();
    u16 prev = 0; u64 loops = 0;
    for (;;) {
        outb(0x43, 0x00);
        u16 cur = (u16)inb(0x40) | ((u16)inb(0x40) << 8);
        if (cur > prev && loops > 10) break;
        prev = cur; loops++;
    }
    u64 tsc_end = rdtsc_dsk();
    g_tsc_per_ms = (tsc_end - tsc_start) / 10;
    logh("[DSK] tsc_per_ms=", g_tsc_per_ms);
}

static u32 blend_color(u32 c1, u32 c2, u32 a) {
    u32 na = 256 - a;
    u32 r = ((c1 & 0xFF) * na + (c2 & 0xFF) * a) >> 8;
    u32 g = (((c1 >> 8) & 0xFF) * na + ((c2 >> 8) & 0xFF) * a) >> 8;
    u32 b = (((c1 >> 16) & 0xFF) * na + ((c2 >> 16) & 0xFF) * a) >> 8;
    return 0xFF000000 | (b << 16) | (g << 8) | r;
}

static u32 dsk_bg_at_y(i64 y) {
    if (g_fb_h <= 1) return BG_TOP;
    if (y < 0) y = 0;
    if ((u64)y >= g_fb_h) y = (i64)g_fb_h - 1;
    return blend_color(BG_TOP, BG_BOTTOM, (u32)(((u64)y * 255ULL) / (g_fb_h - 1)));
}

static void dsk_fill_gradient_rect(u32 *fb, i64 x, i64 y, i64 w, i64 h) {
    for (i64 r = 0; r < h; r++) {
        i64 yy = y + r;
        if (yy < 0 || (u64)yy >= g_fb_h) continue;
        u32 color = dsk_bg_at_y(yy);
        u32 *line = (u32 *)((u8 *)fb + (u64)yy * g_fb_p);
        for (i64 c = 0; c < w; c++) {
            i64 xx = x + c;
            if (xx < 0 || (u64)xx >= g_fb_w) continue;
            line[(u64)xx] = color;
        }
    }
}

/* ---- Spinner animation (removed — replaced by static Logo.png display) ---- */

/* ---- Logo rendering: center RGBA image with alpha blending on gradient bg ----
 * g_logo_rgba / g_logo_w / g_logo_h are from logo_data.c (included above).
 * Source pixel format: RGBA8888 (R at byte 0, G byte 1, B byte 2, A byte 3).
 * Framebuffer format: UEFI BGRX — u32 = 0xAARRGGBB
 *   bits 0-7 = B, bits 8-15 = G, bits 16-23 = R, bits 24-31 = A/X
 */
static void dsk_draw_logo(u32 *fb) {
    /* Center the logo on screen */
    i64 ox = ((i64)g_fb_w - g_logo_w) / 2;
    i64 oy = ((i64)g_fb_h - g_logo_h) / 2;

    for (int ly = 0; ly < g_logo_h; ly++) {
        i64 fy = oy + ly;
        if (fy < 0 || (u64)fy >= g_fb_h) continue;
        u32 *line = (u32 *)((u8 *)fb + (u64)fy * g_fb_p);

        for (int lx = 0; lx < g_logo_w; lx++) {
            i64 fx = ox + lx;
            if (fx < 0 || (u64)fx >= g_fb_w) continue;

            /* Read RGBA pixel from embedded data */
            int idx = (ly * g_logo_w + lx) * 4;
            u8 r = g_logo_rgba[idx + 0];
            u8 g = g_logo_rgba[idx + 1];
            u8 b = g_logo_rgba[idx + 2];
            u8 a = g_logo_rgba[idx + 3];

            if (a == 0) continue;   /* fully transparent: skip */
            if (a == 255) {
                /* fully opaque: BGRX = 0xFF000000 | (R<<16) | (G<<8) | B */
                line[(u64)fx] = 0xFF000000u | ((u32)r << 16) | ((u32)g << 8) | b;
            } else {
                /* alpha blend with background (BGRX channel order) */
                u32 bg = line[(u64)fx];
                u32 na = 256 - a;
                u32 ob = (((bg & 0xFF)       * na + (u32)b * a) >> 8) & 0xFF;
                u32 og = ((((bg >> 8) & 0xFF) * na + (u32)g * a) >> 8) & 0xFF;
                u32 or = ((((bg >> 16)& 0xFF) * na + (u32)r * a) >> 8) & 0xFF;
                line[(u64)fx] = 0xFF000000u | (or << 16) | (og << 8) | ob;
            }
        }
    }
}

/* ---- Text rendering: ASCII bitmap font on framebuffer ----
 * Uses g_ascii[95][11*18] from ascii_bitmaps.c (Consolas 18px).
 * Framebuffer format: BGRX — u32 = 0xAARRGGBB.
 */
static void dsk_draw_char(u32 *fb, char ch, i64 x, i64 y, u32 fg) {
    u32 idx = (u32)(ch - ' ');
    if (idx > 94) idx = 0;
    const u8 *glyph = g_ascii[idx];
    for (int r = 0; r < g_ascii_h; r++) {
        i64 yy = y + r;
        if (yy < 0 || (u64)yy >= g_fb_h) continue;
        u32 *line = (u32 *)((u8 *)fb + (u64)yy * g_fb_p);
        for (int c = 0; c < g_ascii_w; c++) {
            u8 a = glyph[r * g_ascii_w + c];
            if (a == 0) continue;
            i64 xx = x + c;
            if (xx < 0 || (u64)xx >= g_fb_w) continue;
            if (a == 255) {
                line[(u64)xx] = fg;
            } else {
                /* alpha blend with background */
                u32 bg = line[(u64)xx];
                u32 na = 256 - a;
                u32 ob = (((bg & 0xFF)       * na + ((fg & 0xFF)       ) * a) >> 8) & 0xFF;
                u32 og = ((((bg >> 8) & 0xFF) * na + (((fg >> 8) & 0xFF)) * a) >> 8) & 0xFF;
                u32 or = ((((bg >> 16)& 0xFF) * na + (((fg >> 16)& 0xFF)) * a) >> 8) & 0xFF;
                line[(u64)xx] = 0xFF000000u | (or << 16) | (og << 8) | ob;
            }
        }
    }
}

static void dsk_draw_string(u32 *fb, const char *s, i64 x, i64 y, u32 fg, int spacing) {
    i64 cx = x;
    while (*s) {
        dsk_draw_char(fb, *s, cx, y, fg);
        cx += spacing;
        s++;
    }
}

static int fat32_find_entry(const u8 *clus, u32 clus_sectors, const char *target, u32 *out_clus, u32 *out_size) {
    const fat32_de *dir = (const fat32_de *)clus;
    for (u32 e=0; e*32 < clus_sectors*512; e++) {
        if (dir[e].name[0]==0) break;
        if ((u8)dir[e].name[0]==0xE5) continue;
        if (dir[e].attr==0x0F) continue;
        if (dir[e].attr & 0x08) continue;
        if (neq11(dir[e].name, target)) {
            *out_clus = r16((const u8*)&dir[e].clow) | ((u32)r16((const u8*)&dir[e].chigh) << 16);
            *out_size = dir[e].fsize;
            return 0;
        }
    }
    return -1;
}

/* find a single file in root directory by 11-char 8.3 name (avoids PIE pointer reloc) */
static int fat32_read_root_file(const char *name11, u8 **out_data, u32 *out_size) {
    u8 *disk = g_disk;
    DSK_TS_DECL(fat32_root_read);
    DSK_TS_BEGIN(fat32_root_read);
    logl("[DSK] fat32 reading 256 sectors from LBA 0");
    int st = fat32_read_sectors(0, 256, disk);
    logh("[DSK] fat32 read_sectors rc=", (u64)(i64)st);
    if (st != 0) { logl("[DSK] fat32_read_root_file: BPB read failed"); return -1; }
    const fat32_bpb *bpb = (const fat32_bpb *)disk;
    if (bpb->boot_sig != 0xAA55 || bpb->bps != 512) { logl("[DSK] fat32_read_root_file: bad BPB sig/bps"); return -2; }
    if (bpb->spf == 0 || bpb->root_clus < 2) { logh("[DSK] fat32_read_root_file: bad spf/root_clus spf=", (u64)bpb->spf); return -3; }

    u32 data_lba = bpb->rsvd + (u32)bpb->fc * bpb->spf;
    u32 fat_byte_off = bpb->rsvd * 512;
    u32 spc = bpb->spc;
    logh("[DSK] fat32 data_lba=", data_lba);

    /* walk root directory cluster chain */
    u32 clus = bpb->root_clus;
    u32 found_clus = 0, found_size = 0;
    int found = 0;
    while (clus >= 2 && clus < 0x0FFFFFF8 && !found) {
        u32 lba = data_lba + (clus - 2) * spc;
        const u8 *cb;
        if ((u64)lba * 512 + (u64)spc * 512 <= 256ULL * 512)
            cb = disk + (u64)lba * 512;
        else {
            if (fat32_read_sectors(lba, 8, g_cluster) != 0) { logh("[DSK] fat32_read_root_file: dir cluster read failed lba=", (u64)lba); return -4; }
            cb = g_cluster;
        }
        if (fat32_find_entry(cb, spc, name11, &found_clus, &found_size) == 0) { found = 1; break; }
        /* BUG-019: 使用按需 FAT 读取 */
        clus = fat32_get_next_cluster(fat_byte_off, clus, bpb->rsvd);
    }
    if (!found) { logl("[DSK] fat32 entry not found: "); swrite(name11); swrite("\n"); return -5; }
    logh("[DSK] fat32 found_clus=", found_clus);
    logh("[DSK] fat32 found_size=", found_size);

    if (found_size > sizeof(g_fdata)) { logh("[DSK] fat32_read_root_file: file too large size=", (u64)found_size); return -6; }
    u8 *dst = g_fdata; u32 remaining = found_size; u32 fc = found_clus;
    while (fc >= 2 && fc < 0x0FFFFFF8 && remaining > 0) {
        u32 fc_lba = data_lba + (fc - 2) * spc;
        u32 fc_bytes = spc * 512;
        if (fc_bytes > remaining) fc_bytes = remaining;
        const u8 *fb;
        if ((u64)fc_lba * 512 + (u64)spc * 512 <= 256ULL * 512)
            fb = disk + (u64)fc_lba * 512;
        else {
            if (fat32_read_sectors(fc_lba, 8, g_cluster) != 0) { logh("[DSK] fat32_read_root_file: data cluster read failed lba=", (u64)fc_lba); return -7; }
            fb = g_cluster;
        }
        for (u32 b = 0; b < fc_bytes; b++) dst[b] = fb[b];
        dst += fc_bytes; remaining -= fc_bytes;
        /* BUG-019: 使用按需 FAT 读取 */
        fc = fat32_get_next_cluster(fat_byte_off, fc, bpb->rsvd);
    }
    *out_data = g_fdata; *out_size = found_size;
    DSK_TS_END(fat32_root_read, "fat32_read_root_file");
    logl("[DSK] fat32 file read done");
    return 0;
}

/* Write a file to the FAT32 root directory by 11-char 8.3 name.
 * If the file exists, its content is replaced. If not, a new entry is created.
 * Uses g_disk (256-sector buffer) which must already contain the BPB+FAT+root.
 * Returns 0 on success. */
static int fat32_write_root_file(const char *name11, const u8 *data, u32 size) {
    u8 *disk = g_disk;
    const fat32_bpb *bpb = (const fat32_bpb *)disk;
    if (bpb->boot_sig != 0xAA55 || bpb->bps != 512) return -1;
    u32 spc = bpb->spc;
    u32 fat_lba = bpb->rsvd;
    u32 fat_sectors = bpb->spf;
    u32 data_lba = bpb->rsvd + (u32)bpb->fc * bpb->spf;
    u32 fat_byte_off = bpb->rsvd * 512;
    u32 root_clus = bpb->root_clus;
    u32 cluster_bytes = spc * 512;

    /* 1. Re-read BPB+FAT to ensure g_disk is fresh */
    if (fat32_read_sectors(0, 256, disk) != 0) return -2;

    /* 2. Find file entry in root directory — scan ALL clusters in FAT chain */
    u32 cur_clus = root_clus;
    int free_entry = -1;
    u32 free_clus = 0;      /* cluster number where free entry was found */
    u32 existing_clus = 0;
    int found = 0;
    u32 found_clus = 0;     /* cluster number where existing file was found */
    while (cur_clus >= 2 && cur_clus < 0x0FFFFFF8) {
        u32 clus_lba = data_lba + (cur_clus - 2) * spc;
        int in_buf = ((u64)clus_lba * 512 + cluster_bytes <= 256ULL * 512);
        u8 *buf;
        if (in_buf) {
            buf = disk + (u64)clus_lba * 512;
        } else {
            if (fat32_read_sectors(clus_lba, spc, g_milestone_buf) != 0) {
                logl("[DSK] fat32 write: root dir cluster read failed");
                break;
            }
            buf = g_milestone_buf;
        }
        u32 me = cluster_bytes / 32;
        fat32_de *d = (fat32_de *)buf;
        int cluster_done = 0;
        for (u32 e = 0; e < me; e++) {
            if (d[e].name[0] == 0) {
                if (free_entry < 0) { free_entry = (int)e; free_clus = cur_clus; }
                cluster_done = 1; break;
            }
            if ((u8)d[e].name[0] == 0xE5) {
                if (free_entry < 0) { free_entry = (int)e; free_clus = cur_clus; }
                continue;
            }
            if (d[e].attr == 0x0F) continue;
            if (d[e].attr & 0x08) continue;
            if (neq11(d[e].name, name11)) {
                existing_clus = r16((const u8*)&d[e].clow) | ((u32)r16((const u8*)&d[e].chigh) << 16);
                found = 1; found_clus = cur_clus;
                cluster_done = 1; break;
            }
        }
        if (cluster_done) break;
        cur_clus = fat32_get_next_cluster(fat_byte_off, cur_clus, bpb->rsvd);
    }

    /* Re-read the active cluster (the one we'll modify) into root_buf */
    u32 active_clus = found ? found_clus : free_clus;
    u32 root_lba;
    int root_in_buffer;
    u8 *root_buf;
    fat32_de *dir;
    u32 max_entries = cluster_bytes / 32;
    if (active_clus >= 2) {
        root_lba = data_lba + (active_clus - 2) * spc;
        root_in_buffer = ((u64)root_lba * 512 + cluster_bytes <= 256ULL * 512);
        if (root_in_buffer) {
            root_buf = disk + (u64)root_lba * 512;
        } else {
            if (fat32_read_sectors(root_lba, spc, g_milestone_buf) != 0) {
                logl("[DSK] fat32 write: root dir re-read failed");
                return -10;
            }
            root_buf = g_milestone_buf;
        }
        dir = (fat32_de *)root_buf;
    } else {
        root_lba = 0; root_in_buffer = 0; root_buf = 0; dir = 0;
    }

    /* 3. Allocate or reuse clusters */
    u32 bytes_needed = size > 0 ? size : 1;
    u32 clusters_needed = (bytes_needed + cluster_bytes - 1) / cluster_bytes;
    u32 first_clus = 0;
    u32 prev_clus = 0;

    if (found && existing_clus >= 2) {
        /* Reuse existing chain, extend or shrink as needed */
        first_clus = existing_clus;
        u32 cur = existing_clus;
        u32 count = 0;
        while (cur >= 2 && cur < 0x0FFFFFF8 && count < clusters_needed) {
            prev_clus = cur;
            u32 fo = fat_byte_off + cur * 4;
            if (fo + 4 > sizeof(g_disk)) break;
            cur = r32(disk + fo) & 0x0FFFFFFF;
            count++;
        }
        /* If we need more clusters, allocate them */
        while (count < clusters_needed) {
            /* Find a free cluster in FAT */
            u32 newc = 0;
            for (u32 c = 2; c < (fat_sectors * 512) / 4; c++) {
                u32 fo = fat_byte_off + c * 4;
                if (fo + 4 > sizeof(g_disk)) break;
                if ((r32(disk + fo) & 0x0FFFFFFF) == 0) { newc = c; break; }
            }
            if (newc == 0) { logl("[DSK] fat32 write: no free clusters"); return -3; }
            /* BUG-20260730: Mark newly allocated cluster as EOC immediately to prevent re-allocation */
            {
                u32 nfo = fat_byte_off + newc * 4;
                if (nfo + 4 <= sizeof(g_disk)) {
                    disk[nfo] = 0xF8; disk[nfo+1] = 0xFF; disk[nfo+2] = 0xFF; disk[nfo+3] = (disk[nfo+3] & 0xF0) | 0x0F;
                }
            }
            /* Link previous cluster to new */
            u32 pfo = fat_byte_off + prev_clus * 4;
            if (pfo + 4 <= sizeof(g_disk)) {
                disk[pfo] = (u8)(newc & 0xFF);
                disk[pfo+1] = (u8)((newc >> 8) & 0xFF);
                disk[pfo+2] = (u8)((newc >> 16) & 0xFF);
                disk[pfo+3] = (disk[pfo+3] & 0xF0) | (u8)((newc >> 24) & 0x0F);
            }
            prev_clus = newc;
            count++;
        }
        /* BUG-20260730: Terminate the chain, saving original next pointer before overwriting with EOC */
        if (prev_clus >= 2) {
            u32 fo = fat_byte_off + prev_clus * 4;
            u32 original_next = 0;
            if (fo + 4 <= sizeof(g_disk)) {
                original_next = r32(disk + fo) & 0x0FFFFFFF;
                disk[fo] = 0xF8; disk[fo+1] = 0xFF; disk[fo+2] = 0xFF; disk[fo+3] = (disk[fo+3] & 0xF0) | 0x0F;
            }
            /* Free excess clusters from the old chain using saved pointer */
            u32 next = original_next;
            while (next >= 2 && next < 0x0FFFFFF8) {
                u32 nfo = fat_byte_off + next * 4;
                u32 nn = 0;
                if (nfo + 4 <= sizeof(g_disk)) nn = r32(disk + nfo) & 0x0FFFFFFF;
                if (nfo + 4 <= sizeof(g_disk)) { disk[nfo] = 0; disk[nfo+1] = 0; disk[nfo+2] = 0; disk[nfo+3] = disk[nfo+3] & 0xF0; }
                next = nn;
            }
        }
    } else {
        /* Allocate new clusters */
        if (free_entry < 0) { logl("[DSK] fat32 write: no free dir entry"); return -4; }
        for (u32 i = 0; i < clusters_needed; i++) {
            u32 newc = 0;
            for (u32 c = 2; c < (fat_sectors * 512) / 4; c++) {
                u32 fo = fat_byte_off + c * 4;
                if (fo + 4 > sizeof(g_disk)) break;
                if ((r32(disk + fo) & 0x0FFFFFFF) == 0) { newc = c; break; }
            }
            if (newc == 0) { logl("[DSK] fat32 write: no free clusters"); return -3; }
            /* BUG-20260730: Mark newly allocated cluster as EOC immediately to prevent re-allocation */
            {
                u32 nfo = fat_byte_off + newc * 4;
                if (nfo + 4 <= sizeof(g_disk)) {
                    disk[nfo] = 0xF8; disk[nfo+1] = 0xFF; disk[nfo+2] = 0xFF; disk[nfo+3] = (disk[nfo+3] & 0xF0) | 0x0F;
                }
            }
            if (i == 0) first_clus = newc;
            if (prev_clus >= 2) {
                u32 pfo = fat_byte_off + prev_clus * 4;
                if (pfo + 4 <= sizeof(g_disk)) {
                    disk[pfo] = (u8)(newc & 0xFF);
                    disk[pfo+1] = (u8)((newc >> 8) & 0xFF);
                    disk[pfo+2] = (u8)((newc >> 16) & 0xFF);
                    disk[pfo+3] = (disk[pfo+3] & 0xF0) | (u8)((newc >> 24) & 0x0F);
                }
            }
            prev_clus = newc;
        }
        /* Terminate chain */
        /* BUG-20260730: Terminate chain preserving high 4 bits */
        if (prev_clus >= 2) {
            u32 fo = fat_byte_off + prev_clus * 4;
            if (fo + 4 <= sizeof(g_disk)) {
                disk[fo] = 0xF8; disk[fo+1] = 0xFF; disk[fo+2] = 0xFF; disk[fo+3] = (disk[fo+3] & 0xF0) | 0x0F;
            }
        }
    }

    /* 4. Write data to clusters */
    u32 remaining = size;
    const u8 *src = data;
    u32 cur = first_clus;
    u32 ci = 0;
    while (cur >= 2 && cur < 0x0FFFFFF8 && ci < clusters_needed) {
        u32 clba = data_lba + (cur - 2) * spc;
        u32 chunk = remaining < cluster_bytes ? remaining : cluster_bytes;
        /* Read cluster into g_cluster, overlay data, write back */
        if ((u64)clba * 512 + cluster_bytes <= 256ULL * 512) {
            /* In g_disk buffer — copy data directly */
            u8 *dst = disk + (u64)clba * 512;
            for (u32 b = 0; b < chunk; b++) dst[b] = src[b];
            for (u32 b = chunk; b < cluster_bytes; b++) dst[b] = 0;
        } else {
            /* Out of buffer — use sector write */
            if (fat32_read_sectors(clba, spc, g_cluster) != 0) return -5;
            for (u32 b = 0; b < chunk; b++) g_cluster[b] = src[b];
            for (u32 b = chunk; b < cluster_bytes; b++) g_cluster[b] = 0;
            if (fat32_write_sectors(clba, spc, g_cluster) != 0) return -6;
        }
        src += chunk; remaining -= chunk; ci++;
        u32 fo = fat_byte_off + cur * 4;
        if (fo + 4 > sizeof(g_disk)) break;
        cur = r32(disk + fo) & 0x0FFFFFFF;
    }

    /* 5. Update directory entry */
    if (!found) {
        fat32_de *e = &dir[free_entry];
        for (int i = 0; i < 11; i++) e->name[i] = name11[i];
        e->attr = 0x20;  /* archive */
        e->ntr = 0; e->ctenth = 0; e->ctime = 0; e->cdate = 0;
        e->adate = 0; e->chigh = (u16)((first_clus >> 16) & 0xFFFF);
        e->wtime = 0; e->wdate = 0; e->clow = (u16)(first_clus & 0xFFFF);
        e->fsize = size;
    } else {
        /* 文件已存在：只更新匹配到的条目（不触碰 free_entry！） */
        for (u32 e2 = 0; e2 < max_entries; e2++) {
            if (neq11(dir[e2].name, name11)) {
                dir[e2].chigh = (u16)((first_clus >> 16) & 0xFFFF);
                dir[e2].clow = (u16)(first_clus & 0xFFFF);
                dir[e2].fsize = size;
                break;
            }
        }
    }

    /* 6. Write FAT + root directory + data sectors back to disk */
    /* BUG-20260730: Only write back FAT sectors within g_disk buffer bounds */
    {
        u32 max_fat_sectors_in_buffer = (256 - fat_lba) / fat_sectors;
        if (max_fat_sectors_in_buffer > bpb->fc) max_fat_sectors_in_buffer = bpb->fc;
        for (u32 f = 0; f < max_fat_sectors_in_buffer; f++) {
            u32 flba = fat_lba + f * fat_sectors;
            u32 sectors_to_write = fat_sectors;
            if (flba + sectors_to_write > 256) sectors_to_write = 256 - flba;
            if (sectors_to_write > 0 && flba < 256) {
                if (fat32_write_sectors(flba, sectors_to_write, disk + (u64)flba * 512) != 0) return -7;
            }
        }
    }
    /* Write root directory cluster that was modified */
    {
        if (root_in_buffer) {
            if (fat32_write_sectors(root_lba, spc, disk + (u64)root_lba * 512) != 0) return -8;
        } else {
            if (fat32_write_sectors(root_lba, spc, g_milestone_buf) != 0) {
                logl("[DSK] fat32 write: root dir write failed (bounce buffer)");
                return -8;
            }
        }
    }
    /* Write data clusters that were in the g_disk buffer */
    cur = first_clus;
    ci = 0;
    while (cur >= 2 && cur < 0x0FFFFFF8 && ci < clusters_needed) {
        u32 clba = data_lba + (cur - 2) * spc;
        if ((u64)clba * 512 + cluster_bytes <= 256ULL * 512) {
            if (fat32_write_sectors(clba, spc, disk + (u64)clba * 512) != 0) return -9;
        }
        u32 fo = fat_byte_off + cur * 4;
        if (fo + 4 > sizeof(g_disk)) break;
        cur = r32(disk + fo) & 0x0FFFFFFF;
        ci++;
    }

    logl("[DSK] fat32 write: success");
    return 0;
}

/* Write a file into a directory identified by dir_clus, by 11-char 8.3 name.
 * If the file exists, its content is replaced. If not, a new entry is created.
 * Content must fit in one cluster (optimized for small marker files).
 * Uses g_disk (BPB+FAT) and g_cluster (dir) and g_milestone_buf (data).
 * Returns 0 on success. */
static int fat32_write_file_in_dir(u32 dir_clus, const char *name11, const u8 *data, u32 size) {
    u8 *disk = g_disk;
    const fat32_bpb *bpb = (const fat32_bpb *)disk;
    if (bpb->boot_sig != 0xAA55 || bpb->bps != 512) return -1;
    u32 spc = bpb->spc;
    u32 fat_lba = bpb->rsvd;
    u32 fat_sectors = bpb->spf;
    u32 data_lba = bpb->rsvd + (u32)bpb->fc * bpb->spf;
    u32 fat_byte_off = bpb->rsvd * 512;
    u32 cluster_bytes = spc * 512;
    if (size > cluster_bytes) return -1;  /* content must fit in one cluster */

    /* 1. Re-read BPB+FAT to ensure g_disk is fresh */
    if (fat32_read_sectors(0, 256, disk) != 0) return -2;

    /* 2. Read directory cluster */
    u32 dir_lba = data_lba + (dir_clus - 2) * spc;
    if (fat32_read_sectors(dir_lba, spc, g_cluster) != 0) return -3;

    /* 3. Find existing entry or free slot */
    u32 max_entries = cluster_bytes / 32;
    fat32_de *dir = (fat32_de *)g_cluster;
    int free_entry = -1;
    u32 existing_clus = 0;
    int found = 0;
    for (u32 e = 0; e < max_entries; e++) {
        if (dir[e].name[0] == 0) { if (free_entry < 0) free_entry = (int)e; break; }
        if ((u8)dir[e].name[0] == 0xE5) { if (free_entry < 0) free_entry = (int)e; continue; }
        if (dir[e].attr == 0x0F) continue;
        if (dir[e].attr & 0x08) continue;
        if (neq11(dir[e].name, name11)) {
            existing_clus = r16((const u8*)&dir[e].clow) | ((u32)r16((const u8*)&dir[e].chigh) << 16);
            found = 1;
            break;
        }
    }
    if (!found && free_entry < 0) return -4;

    /* 4. Allocate or reuse data cluster */
    u32 file_clus = 0;
    if (found && existing_clus >= 2) {
        file_clus = existing_clus;
    } else {
        /* Find free cluster in FAT */
        for (u32 c = 2; c < (fat_sectors * 512) / 4; c++) {
            u32 fo = fat_byte_off + c * 4;
            if (fo + 4 > sizeof(g_disk)) break;
            if ((r32(disk + fo) & 0x0FFFFFFF) == 0) { file_clus = c; break; }
        }
        if (file_clus == 0) return -5;
        /* BUG-20260730: Mark as end-of-chain in FAT, preserving high 4 bits */
        u32 fo = fat_byte_off + file_clus * 4;
        if (fo + 4 <= sizeof(g_disk)) {
            disk[fo] = 0xF8; disk[fo+1] = 0xFF; disk[fo+2] = 0xFF; disk[fo+3] = (disk[fo+3] & 0xF0) | 0x0F;
        }
    }

    /* 5. Write file data to cluster */
    u32 file_lba = data_lba + (file_clus - 2) * spc;
    for (u32 b = 0; b < size; b++) g_milestone_buf[b] = data[b];
    for (u32 b = size; b < cluster_bytes; b++) g_milestone_buf[b] = 0;
    if (fat32_write_sectors(file_lba, spc, g_milestone_buf) != 0) return -6;

    /* 6. Update directory entry */
    if (found) {
        for (u32 e = 0; e < max_entries; e++) {
            if (neq11(dir[e].name, name11)) {
                dir[e].chigh = (u16)((file_clus >> 16) & 0xFFFF);
                dir[e].clow = (u16)(file_clus & 0xFFFF);
                dir[e].fsize = size;
                break;
            }
        }
    } else {
        fat32_de *e = &dir[free_entry];
        for (int i = 0; i < 11; i++) e->name[i] = name11[i];
        e->attr = 0x20;  /* archive */
        e->ntr = 0; e->ctenth = 0; e->ctime = 0; e->cdate = 0;
        e->adate = 0; e->chigh = (u16)((file_clus >> 16) & 0xFFFF);
        e->wtime = 0; e->wdate = 0; e->clow = (u16)(file_clus & 0xFFFF);
        e->fsize = size;
    }

    /* 7. Write directory cluster back */
    if (fat32_write_sectors(dir_lba, spc, g_cluster) != 0) return -7;

    /* BUG-20260730: Only write back FAT sectors within g_disk buffer bounds */
    {
        u32 max_fat_sectors_in_buffer = (256 - fat_lba) / fat_sectors;
        if (max_fat_sectors_in_buffer > bpb->fc) max_fat_sectors_in_buffer = bpb->fc;
        for (u32 f = 0; f < max_fat_sectors_in_buffer; f++) {
            u32 flba = fat_lba + f * fat_sectors;
            u32 sectors_to_write = fat_sectors;
            if (flba + sectors_to_write > 256) sectors_to_write = 256 - flba;
            if (sectors_to_write > 0 && flba < 256) {
                if (fat32_write_sectors(flba, sectors_to_write, disk + (u64)flba * 512) != 0) return -8;
            }
        }
    }

    logl("[DSK] fat32 write_in_dir: success");
    return 0;
}

/* ---- DSK 启动链里程碑标记系统 ----
 * 实机测试崩溃定位：每个启动阶段成功后写标记文件到 FAT32。
 * 命名：BOOT01.TXT ~ BOOT07.TXT（8.3 短名）。
 * 目标目录：DESHAB64/DEV/（不存在时回退根目录）。
 * 写入失败静默忽略，不影响启动流程。
 *
 * 阶段定义:
 *   BOOT_01: FAT32 文件系统就绪
 *   BOOT_02: block_read/block_write API 就绪
 *   BOOT_03: FUCK 配置加载完成
 *   BOOT_04: firstInit 检查完成
 *   BOOT_05: dev_mode shell 加载完成
 *   BOOT_06: desktop.elf 加载完成
 *   BOOT_07: 网络管理器加载完成 */
static void milestone_write(int num, const char *desc) {
    if (!g_block_write) return;
    if (num < 1 || num > 9) return;
    /* 构造 8.3 短名: "BOOTnn  TXT" (FAT 8.3 format, 11 chars) */
    char name11[12];
    name11[0]='B'; name11[1]='O'; name11[2]='O'; name11[3]='T';
    name11[4]=(char)('0' + (num / 10));
    name11[5]=(char)('0' + (num % 10));
    name11[6]=' '; name11[7]=' ';
    name11[8]='T'; name11[9]='X'; name11[10]='T';
    /* 构造内容: "OK\n" + desc + "\n" */
    /* BUG-20260730: Enlarge buffer — "OK\n" + stage desc + " tsc=0x" + 16-hex + " ms=" + digits + "\n" can exceed 64 */
    u8 buf[160];
    u32 len = 0;
    buf[len++]='O'; buf[len++]='K'; buf[len++]='\n';
    while (*desc && len < 150) buf[len++] = (u8)*desc++;
    buf[len++] = '\n';
    /* 确保 BPB 在 g_disk 中可用 */
    if (fat32_read_sectors(0, 256, g_disk) != 0) return;
    /* 尝试写入 DESHAB64/DEV/ 目录，不存在则回退根目录 */
    u32 dev_clus = fat32_find_dir_cluster("SYSTEM  /DESHAB64 /DEV     ");
    int rc;
    if (dev_clus >= 2) {
        rc = fat32_write_file_in_dir(dev_clus, name11, buf, len);
    } else {
        rc = fat32_write_root_file(name11, buf, len);
    }
    if (rc == 0) {
        swrite("[DSK] milestone BOOT_0");
        sputc('0' + num);
        logl(dev_clus >= 2 ? " written (DEV)" : " written (root)");
    }
}

static int dsk_check_firstinit(int *is_first, int *dev_mode) {
    DSK_TS_DECL(firstinit_check);
    DSK_TS_BEGIN(firstinit_check);
    char name[12]; /* "FIRSTINTXT" on stack — no PIE reloc */
    name[0]='F';name[1]='I';name[2]='R';name[3]='S';name[4]='T';
    name[5]='I';name[6]='N';name[7]='T';name[8]='X';name[9]='T';name[10]=0;
    u8 *data = 0; u32 size = 0;
    *dev_mode = 0;
    logl("[DSK] fat32_read_path start");
    int rc = fat32_read_root_file(name, &data, &size);
    logh("[DSK] fat32_read_path rc=", (u64)(i64)rc);
    if (rc != 0) { logl("[DSK] firstInit.txt not found, assuming first boot"); *is_first = 1; DSK_TS_END(firstinit_check, "dsk_check_firstinit (not found)"); return 0; }
    if (data[0] == '0') { logl("[DSK] firstInit=0"); *is_first = 1; }
    else { logl("[DSK] firstInit != 0"); *is_first = 0; }
    /* 解析第二行 dev_mode 标志（firstInit.txt 格式: "0|1\n0|1"） */
    u32 i = 0;
    while (i < size && data[i] != '\n') i++;
    if (i < size) {
        i++;  /* 跳过换行 */
        if (i < size && data[i] == '1') {
            *dev_mode = 1;
            logl("[DSK] dev_mode=1 (developer auto-test)");
        }
    }
    DSK_TS_END(firstinit_check, "dsk_check_firstinit");
    return 0;
}

static int dsk_load_elf(u8 *data, u32 size, void **entry_out) {
    DSK_TS_DECL(elf_load);
    DSK_TS_BEGIN(elf_load);
    DSK_STAT_INC(elf_load);
    const elf64_ehdr *eh = (const elf64_ehdr *)data;
    if (size < sizeof(elf64_ehdr)) { logl("[DSK] ELF: data too small"); return -1; }
    if (eh->ident[0] != EI_MAG0 || eh->ident[4] != ELFCLASS64) { logl("[DSK] ELF: bad magic/class"); return -1; }
    if (eh->machine != EM_X86_64) { logl("[DSK] ELF: wrong machine"); return -2; }
    /* P0 修复: 验证程序头在数据范围内 */
    if (eh->phoff == 0 || eh->phnum == 0) { logl("[DSK] ELF: no program headers"); return -3; }
    if ((u64)eh->phoff + (u64)eh->phnum * (u64)eh->phentsize > (u64)size) {
        logl("[DSK] ELF: program headers beyond data bounds");
        return -4;
    }
    u64 min_vaddr = ~0ULL, max_vaddr = 0;
    u32 lc = 0;
    for (u16 i = 0; i < eh->phnum; i++) {
        const elf64_phdr *ph = (const elf64_phdr *)(data + eh->phoff + (u64)i * eh->phentsize);
        if (ph->type != PT_LOAD) continue;
        if (ph->filesz > ph->memsz) { logl("[DSK] ELF: filesz > memsz"); return -5; }
        /* P0 修复: 验证 PT_LOAD 段在数据范围内 */
        if ((u64)ph->offset + (u64)ph->filesz > (u64)size) {
            logl("[DSK] ELF: PT_LOAD beyond data bounds");
            logh("[DSK] ELF: offset=", ph->offset);
            logh("[DSK] ELF: filesz=", ph->filesz);
            return -6;
        }
        if (ph->vaddr < min_vaddr) min_vaddr = ph->vaddr;
        if (ph->vaddr + ph->memsz > max_vaddr) max_vaddr = ph->vaddr + ph->memsz;
        lc++;
    }
    if (!lc || min_vaddr == ~0ULL) { logl("[DSK] ELF: no PT_LOAD segments"); return -7; }
    u64 isize = max_vaddr - min_vaddr;
    isize = (isize + 0xFFF) & ~0xFFFULL;
    logh("[DSK] elf total image size=", isize);
    /* 加载缓冲:需容纳 desktop.elf(~1.67MB memsz span,含 Linux 窗口槽+16KB 缓冲 BSS)。2MB 留余量。 */
    static u8 ibuf[8388608]; /* 8MB — cmd.elf 含 4MB PE 文件缓冲 BSS */
    u8 *image = ibuf;
    if (isize > 8388608) { logl("[DSK] ELF: image too large for 8MB ibuf"); logh("[DSK] ELF isize=", isize); return -8; }
    memset_dsk(image, 0, isize);
    for (u16 i = 0; i < eh->phnum; i++) {
        const elf64_phdr *ph = (const elf64_phdr *)(data + eh->phoff + (u64)i * eh->phentsize);
        if (ph->type != PT_LOAD) continue;
        u64 off = ph->vaddr - min_vaddr;
        logh("[DSK] PT_LOAD vaddr=", ph->vaddr);
        logh("[DSK] PT_LOAD filesz=", ph->filesz);
        logh("[DSK] PT_LOAD memsz=", ph->memsz);
        /* off + filesz 不会越界，已在上面的循环中验证 */
        memcpy_dsk(image + off, data + ph->offset, ph->filesz);
    }
    /* P0 修复: 验证 entry 在映像范围内 */
    if (eh->entry < min_vaddr || eh->entry >= max_vaddr) {
        logl("[DSK] ELF: entry point out of bounds");
        logh("[DSK] ELF: entry=", eh->entry);
        logh("[DSK] ELF: min_vaddr=", min_vaddr);
        logh("[DSK] ELF: max_vaddr=", max_vaddr);
        return -9;
    }
    *entry_out = image + (eh->entry - min_vaddr);

    /* apply R_X86_64_RELATIVE relocations from PT_DYNAMIC (PIE) */
    u64 load_bias = (u64)image - min_vaddr;
    for (u16 i = 0; i < eh->phnum; i++) {
        const elf64_phdr *ph = (const elf64_phdr *)(data + eh->phoff + (u64)i * eh->phentsize);
        if (ph->type != PT_DYNAMIC) continue;
        /* P0 修复: 验证 PT_DYNAMIC vaddr 在映像范围内 */
        if (ph->vaddr < min_vaddr || ph->vaddr + ph->filesz > max_vaddr) {
            logl("[DSK] ELF: PT_DYNAMIC out of image bounds");
            continue;
        }
        const elf64_dyn *dyn = (const elf64_dyn *)(image + (ph->vaddr - min_vaddr));
        u64 rela_off = 0, rela_sz = 0, rela_ent = 24;
        for (; dyn->tag != 0; dyn++) {
            if (dyn->tag == DT_RELA) rela_off = dyn->val;
            else if (dyn->tag == DT_RELASZ) rela_sz = dyn->val;
            else if (dyn->tag == DT_RELAENT) rela_ent = dyn->val;
        }
        if (rela_off && rela_sz) {
            /* P0 修复: 边界检查 rela_off 和 rela_off+rela_sz 必须在 [min_vaddr, min_vaddr+isize) 内 */
            if (rela_off < min_vaddr || rela_off >= min_vaddr + isize) {
                logl("[DSK] ELF: rela_off out of bounds, skipping reloc");
                logh("[DSK] ELF: rela_off=", rela_off);
                logh("[DSK] ELF: min_vaddr=", min_vaddr);
                logh("[DSK] ELF: isize=", isize);
                continue;
            }
            if (rela_off + rela_sz > min_vaddr + isize) {
                logl("[DSK] ELF: rela table extends beyond image, clamping");
                rela_sz = (min_vaddr + isize - rela_off) / rela_ent * rela_ent;
            }
            u64 n = rela_sz / rela_ent;
            logh("[DSK] elf relocs=", n);
            for (u64 r = 0; r < n; r++) {
                const elf64_rela *rel = (const elf64_rela *)(image + (rela_off - min_vaddr) + r * rela_ent);
                u32 rtype = (u32)(rel->info & 0xFFFFFFFF);
                if (rtype == R_X86_64_RELATIVE) {
                    /* P0 修复: 验证 rel->offset 在映像范围内，防止无符号下溢 */
                    if (rel->offset < min_vaddr || rel->offset >= min_vaddr + isize) continue;
                    u64 *slot = (u64 *)(image + (rel->offset - min_vaddr));
                    *slot = load_bias + (u64)rel->addend;
                }
            }
        }
    }

    logh("[DSK] elf image base=", (u64)image);
    logh("[DSK] elf entry=", (u64)*entry_out);
    DSK_TS_END(elf_load, "dsk_load_elf");
    return 0;
}

/* Load an ELF module from the FAT32 root by 11-char 8.3 name, parse it into
 * the shared image buffer, and jump to its entry with the boot context.
 * Returns 0 if the module ran and returned, non-zero on load failure. */
static int dsk_load_and_run(const char name11[12], const dsk_boot_context *ctx) {
    DSK_TS_DECL(mod_run);
    DSK_TS_BEGIN(mod_run);
    DSK_STAT_INC(mod_schedule);
    u8 *data=0; u32 size=0; void *entry=0;
    logl("[DSK] load_and_run: ");
    swrite(name11); swrite("\n");
    if (fat32_read_root_file(name11, &data, &size) != 0) { logl("[DSK] load_and_run: fat32 read failed for "); swrite(name11); swrite("\n"); return -1; }
    if (dsk_load_elf(data, size, &entry) != 0) { logl("[DSK] load_and_run: elf load failed for "); swrite(name11); swrite("\n"); return -2; }
    void(*fn)(const dsk_boot_context*)=(void(*)(const dsk_boot_context*))entry;
    fn(ctx);
    DSK_TS_END(mod_run, "dsk_load_and_run");
    return 0;
}

/* Load desktop.elf and jump to it. Never returns on success. */
static void dsk_run_desktop(const dsk_boot_context *ctx) {
    char dn[12]; /* DESKTOP ELF */
    dn[0]='D';dn[1]='E';dn[2]='S';dn[3]='K';dn[4]='T';dn[5]='O';dn[6]='P';dn[7]=' ';dn[8]='E';dn[9]='L';dn[10]='F';
    if (dsk_load_and_run(dn, ctx) != 0) logl("[DSK] desktop load failed");
    for(;;)__asm__("hlt");
}

/* After FirstInit returns, persist the encrypted user.conf buffer (left in
 * ctx->reserved[0/1]) to the FAT32 root as USER.CONF, then flip firstInit.txt
 * from '0' to '1' so subsequent boots skip the wizard and go to login. */
static void dsk_persist_userconf(const dsk_boot_context *ctx) {
    dsk_boot_context *ctx_mut = (dsk_boot_context *)ctx;
    u64 conf_ptr = ctx_mut->reserved[0];
    u64 conf_sz  = ctx_mut->reserved[1];
    if (!conf_ptr || !conf_sz) {
        logl("[DSK] no conf buffer from FirstInit, skipping persist");
        return;
    }
    if (!g_block_write) {
        logl("[DSK] no block_write, cannot persist user.conf");
        return;
    }
    const u8 *conf = (const u8 *)conf_ptr;

    /* 1. Write USER.CONF (encrypted buffer as-is; login decrypts with password) */
    char cn[12]; /* USER    CON */
    cn[0]='U';cn[1]='S';cn[2]='E';cn[3]='R';cn[4]=' ';cn[5]=' ';cn[6]=' ';cn[7]=' ';cn[8]='C';cn[9]='O';cn[10]='N';
    logl("[DSK] writing USER.CONF");
    int wrc = fat32_write_root_file(cn, conf, (u32)conf_sz);
    logh("[DSK] USER.CONF write rc=", (u64)(i64)wrc);

    /* 2. Flip firstInit.txt: '0' -> '1'，保留第二行 dev_mode 标志 */
    char fn[12]; /* FIRSTINTXT */
    fn[0]='F';fn[1]='I';fn[2]='R';fn[3]='S';fn[4]='T';fn[5]='I';fn[6]='N';fn[7]='T';fn[8]='X';fn[9]='T';fn[10]=0;
    /* 读取当前 firstInit.txt 以保留 dev_mode（第二行），格式 "0|1\n0|1" */
    u8 dev_mode_byte = '0';
    u8 *fi_data = 0; u32 fi_size = 0;
    if (fat32_read_root_file(fn, &fi_data, &fi_size) == 0) {
        u32 i = 0;
        while (i < fi_size && fi_data[i] != '\n') i++;
        if (i < fi_size) { i++; if (i < fi_size) dev_mode_byte = fi_data[i]; }
    }
    u8 fi_buf[3]; fi_buf[0] = '1'; fi_buf[1] = '\n'; fi_buf[2] = dev_mode_byte;
    int frc = fat32_write_root_file(fn, fi_buf, 3);
    logh("[DSK] firstInit.txt flip rc=", (u64)(i64)frc);

    /* Clear reserved so login path doesn't see stale pointer */
    ctx_mut->reserved[0] = 0;
    ctx_mut->reserved[1] = 0;
}

/* Draw the spinning loader (comet-tail arc) on the gradient background,
 * then run the firstInit check and dispatch system component loading.
 * FUCK config controls: show_logo, skip_login, mouse_init, netman, dev_mode. */
static void dsk_spinner_and_check(const void *boot_ctx_ptr) {
    const dsk_boot_context *ctx = (const dsk_boot_context *)boot_ctx_ptr;
    { u64 api_addr = ctx->dkm_kernel_api;
      logh("[DSK] kernel_api addr=", api_addr);
      if (!api_addr) { logl("[DSK] FATAL: kernel_api is NULL"); for(;;)__asm__("hlt"); }
      const dsk_kernel_api_mirror *api = (const dsk_kernel_api_mirror *)api_addr;
      const dsk_block_api_mirror *blk = api->block;
      logh("[DSK] block_api addr=", (u64)(u64)blk);
      g_block_read  = blk ? blk->read  : 0;
      g_block_write = blk ? blk->write : 0;
      logh("[DSK] block_read fn=", (u64)g_block_read);
      logh("[DSK] block_write fn=", (u64)g_block_write); }
    milestone_write(2, "block API ready");

    g_fb_addr=ctx->framebuffer_address; g_fb_w=ctx->framebuffer_width;
    g_fb_h=ctx->framebuffer_height; g_fb_p=ctx->framebuffer_pitch;
    if (!g_fb_addr) { logl("[DSK] FATAL: framebuffer address is NULL"); for(;;)__asm__("hlt"); }
    u32 *sfb=(u32*)(u64)g_fb_addr;
    logh("[DSK] block_read ptr=", (u64)g_block_read);

    tsc_calibrate_dsk();

    /* === 读取 FUCK 配置 === */
    DSK_TS_DECL(fuck_config);
    DSK_TS_BEGIN(fuck_config);
    dsk_ini_config dsk_cfg;
    int dsk_cfg_ok = 0;
    if (g_block_read) {
        logl("[DSK] reading BPB for FUCK config");
        int bpb_rc = fat32_read_sectors(0, 256, g_disk);
        if (bpb_rc == 0) {
            milestone_write(1, "FAT32 ready");
            u8 *fuck_data=0; u32 fuck_size=0;
            int rc = fat32_read_path("SYSTEM  /DESHAB64 /FUCK    ", &fuck_data, &fuck_size);
            logh("[DSK] fat32_read_path FUCK rc=", (u64)(i64)rc);
            if (rc != 0) {
                /* 扁平布局回退：SATA 测试盘等场景下 FUCK 直接放根目录 */
                rc = fat32_read_path("FUCK       ", &fuck_data, &fuck_size);
                logh("[DSK] fat32_read_path root FUCK rc=", (u64)(i64)rc);
            }
            if (rc == 0 && fuck_size > 0) {
                if (dsk_ini_parse((const char *)fuck_data, fuck_size, &dsk_cfg) == 0) {
                    dsk_cfg_ok = 1;
                    logl("[DSK] FUCK config loaded");
                } else {
                    logl("[DSK] FUCK INI parse failed");
                }
            } else {
                logl("[DSK] FUCK file not found or empty");
            }
        } else {
            logl("[DSK] BPB read failed, cannot load FUCK");
        }
    }
    DSK_TS_END(fuck_config, "FUCK config load");

    /* === 应用 DSK 配置 === */
    int show_logo   = dsk_cfg_ok ? dsk_ini_get_bool(&dsk_cfg, "dsk", "show_logo", 1)    : 1;
    int skip_login  = dsk_cfg_ok ? dsk_ini_get_bool(&dsk_cfg, "dsk", "skip_login", 0)   : 0;
    int load_mouse  = dsk_cfg_ok ? dsk_ini_get_bool(&dsk_cfg, "dsk", "mouse_init", 1)   : 1;
    int load_netman = dsk_cfg_ok ? dsk_ini_get_bool(&dsk_cfg, "dsk", "netman", 1)        : 1;
    int dev_mode    = dsk_cfg_ok ? dsk_ini_get_bool(&dsk_cfg, "boot", "dev_mode", 0)     : 0;
    milestone_write(3, "FUCK config loaded");

    /* Gradient background + centered Logo.png (5 seconds) */
    dsk_fill_gradient_rect(sfb, 0, 0, (i64)g_fb_w, (i64)g_fb_h);

    if (show_logo) {
        /* Draw Logo.png centered with alpha blending on gradient background */
        dsk_draw_logo(sfb);

        /* Draw "DESHAB P01" text centered below the logo */
        {
            i64 logo_cx = (i64)g_fb_w / 2;
            i64 logo_cy = ((i64)g_fb_h - g_logo_h) / 2;
            const char *ver_str = "DESHAB P01";
            int len = 10;   /* strlen("DESHAB P01") */
            int spacing = g_ascii_w + 1;   /* 11+1 = 12px per char */
            i64 text_w = (i64)len * spacing;
            i64 text_x = logo_cx - text_w / 2;
            i64 text_y = logo_cy + g_logo_h + 12;  /* 12px below logo */
            /* White text: BGRX = 0xFF_RR_GG_BB = 0xFF_FFFFFF */
            u32 fg = 0xFFFFFFFFu;
            dsk_draw_string(sfb, ver_str, text_x, text_y, fg, spacing);
        }

        logh("[DSK] Logo.png displayed (", (u64)g_logo_w);
        logh("[DSK] x", (u64)g_logo_h);

        /* Hold Logo for 5 seconds */
        u64 logo_start = rdtsc_dsk();
        u64 logo_budget = g_tsc_per_ms * 5000;   /* 5000 ms = 5 seconds */
        while (rdtsc_dsk() - logo_start < logo_budget) __asm__("pause");
        logl("[DSK] Logo 5s done, proceeding");
    } else {
        logl("[DSK] logo skipped by FUCK config");
    }

    if (!g_block_read) {
        logl("[DSK] no block device, halting");
        for(;;)__asm__("hlt");
    }

    logl("[DSK] checking firstInit...");
    DSK_TS_DECL(firstinit_phase);
    DSK_TS_BEGIN(firstinit_phase);
    int is_first = 0, firstinit_dev_mode = 0;
    if (dsk_check_firstinit(&is_first, &firstinit_dev_mode) != 0) {
        logl("[DSK] firstInit check failed, halting");
        for(;;)__asm__("hlt");
    }
    DSK_TS_END(firstinit_phase, "firstInit check phase");
    milestone_write(4, "firstInit check done");

    /* 合并 FUCK dev_mode 和 firstInit.txt dev_mode */
    if (firstinit_dev_mode) dev_mode = 1;

    /* 开发者模式:加载 shell.elf 自动测试命令序列（cp/mv/echo/ls/cat/rm） */
    if (dev_mode) {
        logl("[DSK:SCHED] decision: dev_mode -> shell.elf");
        char sn[12]; /* SHELL   ELF */
        sn[0]='S';sn[1]='H';sn[2]='E';sn[3]='L';sn[4]='L';sn[5]=' ';sn[6]=' ';sn[7]=' ';sn[8]='E';sn[9]='L';sn[10]='F';
        dsk_boot_context *ctx_mut = (dsk_boot_context *)ctx;
        ctx_mut->reserved[3] = 1;  /* dev mode flag for shell */
        if (dsk_load_and_run(sn, ctx) == 0) logl("[DSK] shell auto-test returned");
        else logl("[DSK] shell.elf not found, skipping dev test");
        ctx_mut->reserved[3] = 0;
        milestone_write(5, "dev shell loaded");
    }

    if (!is_first) {
        logl("[DSK:SCHED] decision: is_first=0 -> login then desktop");

        /* login — 可通过 skip_login=1 跳过 */
        if (skip_login) {
            logl("[DSK:SCHED] login skipped by FUCK config");
        } else {
            DSK_TS_DECL(login_phase);
            DSK_TS_BEGIN(login_phase);
            logl("[DSK:SCHED] scheduling login.elf");
            char ln[12]; /* LOGIN    ELF */
            ln[0]='L';ln[1]='O';ln[2]='G';ln[3]='I';ln[4]='N';ln[5]=' ';ln[6]=' ';ln[7]=' ';ln[8]='E';ln[9]='L';ln[10]='F';
            u8 *ld=0; u32 ls=0; void *le=0;
            int login_ok = 0;
            if (fat32_read_root_file(ln, &ld, &ls) == 0) {
                if (dsk_load_elf(ld, ls, &le) == 0) {
                    char cn[12]; /* USER    CON */
                    cn[0]='U';cn[1]='S';cn[2]='E';cn[3]='R';cn[4]=' ';cn[5]=' ';cn[6]=' ';cn[7]=' ';cn[8]='C';cn[9]='O';cn[10]='N';
                    u8 *conf_data=0; u32 conf_size=0;
                    if (fat32_read_root_file(cn, &conf_data, &conf_size) == 0) {
                        logl("[DSK] USER.CONF found, passing to login");
                        dsk_boot_context *ctx_mut = (dsk_boot_context *)ctx;
                        ctx_mut->reserved[0] = (u64)conf_data;
                        ctx_mut->reserved[1] = (u64)conf_size;
                        ctx_mut->reserved[2] = 0;  /* login success flag */

                        logl("[DSK] jumping to login");
                        void(*lentry)(const dsk_boot_context*)=(void(*)(const dsk_boot_context*))le;
                        lentry(ctx);
                        logl("[DSK] login returned");

                        if (ctx_mut->reserved[2] == 1) {
                            logl("[DSK] login success");
                            login_ok = 1;
                        } else {
                            logl("[DSK] login skipped or failed");
                        }
                    } else {
                        logl("[DSK] USER.CONF not found, skipping login");
                    }
                } else {
                    logl("[DSK] login.elf load failed, skipping login");
                }
            } else {
                logl("[DSK] login.elf not found, skipping login");
            }
            (void)login_ok;
            DSK_TS_END(login_phase, "login phase");
        }

        /* default_shell=cmd → 直接进 CMD.ELF（PE/EXE 兼容层前端），
         * cmd 退出后回落桌面。 */
        const char *def_shell = dsk_cfg_ok ? dsk_ini_get(&dsk_cfg, "dsk", "default_shell") : 0;
        if (def_shell && dsk_ini_streq(def_shell, "cmd")) {
            logl("[DSK:SCHED] default_shell=cmd -> cmd.elf");
            char cn[12]; /* CMD      ELF */
            cn[0]='C';cn[1]='M';cn[2]='D';cn[3]=' ';cn[4]=' ';cn[5]=' ';cn[6]=' ';cn[7]=' ';cn[8]='E';cn[9]='L';cn[10]='F';
            if (dsk_load_and_run(cn, ctx) == 0) logl("[DSK] cmd.elf returned, falling back to desktop");
            else logl("[DSK] cmd.elf load failed, falling back to desktop");
        }

        logl("[DSK:SCHED] loading desktop");
        logh("[DSK:STAT] fat32_read_count=", (u64)fat32_read_count);
        logh("[DSK:STAT] fat32_write_count=", (u64)fat32_write_count);
        logh("[DSK:STAT] elf_load_count=", (u64)elf_load_count);
        logh("[DSK:STAT] mod_schedule_count=", (u64)mod_schedule_count);
        milestone_write(6, "desktop loading");
        dsk_run_desktop(ctx);
        return;
    }

    /* First boot: run system initializers, then FirstInit, then desktop */
    logl("[DSK:SCHED] decision: is_first=1 -> mouseInit -> netman -> FirstInit -> desktop");

    /* mouseInit.elf — 可通过 FUCK mouse_init=0 跳过 */
    if (load_mouse) {
        logl("[DSK:SCHED] scheduling mouseInit.elf");
        char mn[12]; /* MOUSE   ELF */
        mn[0]='M';mn[1]='O';mn[2]='U';mn[3]='S';mn[4]='E';mn[5]=' ';mn[6]=' ';mn[7]=' ';mn[8]='E';mn[9]='L';mn[10]='F';
        logl("[DSK] loading mouseInit");
        if (dsk_load_and_run(mn, ctx) == 0) logl("[DSK] mouseInit returned");
        else logl("[DSK] mouseInit not found");
    } else {
        logl("[DSK] mouseInit skipped by FUCK config");
    }

    /* netman.elf — 可通过 FUCK netman=0 跳过 */
    if (load_netman) {
        logl("[DSK:SCHED] scheduling netman.elf");
        char nn[12]; /* NETMAN  ELF */
        nn[0]='N';nn[1]='E';nn[2]='T';nn[3]='M';nn[4]='A';nn[5]='N';nn[6]=' ';nn[7]=' ';nn[8]='E';nn[9]='L';nn[10]='F';
        logl("[DSK] loading netman");
        if (dsk_load_and_run(nn, ctx) == 0) logl("[DSK] netman returned");
        else logl("[DSK] netman not found");
    } else {
        logl("[DSK] netman skipped by FUCK config");
    }
    milestone_write(7, "netman loaded");

    /* FirstInit.elf — user setup wizard; returns to DSK when done */
    {   logl("[DSK:SCHED] scheduling FirstInit.elf");
        char en[12]; /* FIRSTINIT */
        en[0]='F';en[1]='I';en[2]='R';en[3]='S';en[4]='T';
        en[5]='I';en[6]='N';en[7]='I';en[8]='T';en[9]=' ';en[10]=0;
        logl("[DSK] loading FirstInit");
        if (dsk_load_and_run(en, ctx) != 0) {
            logl("[DSK] FirstInit not found, loading desktop directly");
            milestone_write(6, "desktop loading");
            dsk_run_desktop(ctx);
            return;
        }
        logl("[DSK] FirstInit returned, persisting user.conf");
        dsk_persist_userconf(ctx);
        logh("[DSK:STAT] fat32_read_count=", (u64)fat32_read_count);
        logh("[DSK:STAT] fat32_write_count=", (u64)fat32_write_count);
        logh("[DSK:STAT] elf_load_count=", (u64)elf_load_count);
        logh("[DSK:STAT] mod_schedule_count=", (u64)mod_schedule_count);
        logl("[DSK] loading desktop");
        milestone_write(6, "desktop loading");
        dsk_run_desktop(ctx);
    }
}

__attribute__((noreturn, visibility("default")))
void dsk_entry(const dsk_boot_context *ctx) {
    __asm__ volatile("cli");  /* disable IRQs — ps2kbd/IRQ1 & mouse/IRQ12 handlers crash during boot */
    logl("[DSK] boot");
    if(!ctx||ctx->magic!=DSK_BOOT_MAGIC){logl("[DSK] bad context");for(;;)__asm__("hlt");}
    logl("[DSK] context ok");
    dsk_spinner_and_check(ctx);
    logl("[DSK] SELFTEST PASS");
    for(;;)__asm__("hlt");
}