166 lines
5.5 KiB
Markdown
166 lines
5.5 KiB
Markdown
# Linux 6.6 LTS for UTSM Dual-Kernel Architecture
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## Overview
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This directory contains the Linux 6.6 LTS configuration and build scripts for the
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UTSM + Linux dual-kernel architecture. Linux runs as a VMX non-root guest under
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the UTSM hypervisor (VMX root).
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## Prerequisites
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- **WSL** (Windows Subsystem for Linux) with Ubuntu 22.04+ installed
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```powersShell
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wsl --install -d Ubuntu-22.04
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```
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- Build dependencies (inside WSL):
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```bash
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sudo apt update
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sudo apt install -y build-essential bc flex bison libelf-dev libssl-dev cpio gzip git
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```
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- ~3GB free disk space
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## Building Linux
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### 1. From WSL
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```bash
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# Navigate to the project (adjust path for your WSL mount)
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cd /mnt/d/Code/Deshab/CODE/linux
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# Make the build script executable
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chmod +x build.sh
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# Run the build (clones Linux 6.6 LTS, configures, builds)
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./build.sh
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```
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The build will:
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1. Clone Linux 6.6 LTS source to `CODE/linux/src/`
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2. Apply UTSM patches from `CODE/linux/patches/` (if any)
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3. Configure with `configs/utsm_x86_64_defconfig`
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4. Build `bzImage`
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5. Copy to `SYSTEM/boot/linux-bzImage`
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6. Build initramfs if `CODE/linux/initramfs/` exists
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### 2. Enable in Limine
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After building, uncomment the Linux module entries in `SYSTEM/limine/limine.conf`:
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```
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module_path: boot():/boot/linux-bzImage
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module_cmdline: linux:bzImage
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module_path: boot():/boot/linux-initrd.img
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module_cmdline: linux:initrd
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```
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### 3. Rebuild the disk image
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```PowerShell
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cd d:\Code\Deshab
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.\build.bat
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```
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### 4. Test with QEMU
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**Note:** VMX requires hardware virtualization support. QEMU's TCG (software
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emulation) does NOT support VMX instructions. To test the VMX path:
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- **Real hardware**: Boot on an Intel machine with VT-x enabled in BIOS
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- **QEMU with WHPX**: `qemu-system-x86_64 -accel whpx -cpu max` (may not expose
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nested VMX to the guest)
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- **QEMU with KVM** (Linux host only): `qemu-system-x86_64 -enable-kvm -cpu host`
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Without VMX, UTSM gracefully falls back to the normal DSK boot flow.
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## Configuration Details
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The `utsm_x86_64_defconfig` enables:
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- 64-bit kernel with SMP support
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- Serial console (8250/16550 at 0x3F8, 115200 baud)
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- virtio: console, block, net, fs (for UTSM host backends)
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- ext4, FAT, tmpfs, proc, sysfs filesystems
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- No module loading (all drivers built-in for Phase 1)
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- No EFI stub (UTSM uses custom VMX boot protocol)
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- Debug info and printk timestamps
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## File Structure
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```
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CODE/linux/
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├── configs/
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│ └── utsm_x86_64_defconfig # Kernel configuration
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├── patches/ # UTSM-specific kernel patches
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│ ├── utsm-hcall.patch # /dev/utsm hypercall driver (Phase 1.3)
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│ ├── utsm-ipc.patch # Shared memory IPC driver (Phase 1.3)
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│ └── utsm-virtio.patch # virtio enhancements (Phase 1.4+)
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├── initramfs/ # Minimal initramfs contents (optional)
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├── build.sh # Build script (run in WSL/Linux)
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└── README.md # This file
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```
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## Boot Flow
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```
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Limine (UEFI)
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→ utsm.elf (VMX root)
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→ vmm_init() + vmm_self_test()
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→ linux_loader_init() (parse bzImage, set up boot_params, EPT)
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→ linux_launch() (VMCS config + vmlaunch)
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→ Linux 6.6 startup_64 (VMX non-root)
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→ Serial console output
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→ virtio-console ↔ UTSM
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→ virtio-fs mount /utsm
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→ User space (init/shell)
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```
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## Guest Networking (virtio-net)
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UTSM vmm 侧模拟一块 virtio-net 网卡（virtio-mmio 模型，GPA `0xF4001000`，
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guest ISA IRQ6），数据路径桥接到 host 真实网卡（e1000/virtio-net DKM 驱动，
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经 `kernel_api.net` 的 `tx`/`rx_poll` 收发帧）。guest 内核 cmdline 已自动注入：
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```
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virtio_mmio.device=4K@0xF4001000:6
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```
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`utsm_x86_64_defconfig` 已启用 `CONFIG_VIRTIO_NET=y`（内置，非模块），
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内核启动后应出现 `eth0`（virtio-mmio 无 PCI 拓扑，网卡名固定为 eth0）：
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```bash
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# 确认网卡已识别（dmesg 应能看到 virtio_net probe 日志）
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ip link show
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# 拉起接口
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ip link set eth0 up
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# 方式一：DHCP（QEMU user-net/slirp 环境，网关 10.0.2.2，DNS 10.0.2.3）
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dhcpcd eth0
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# 或：dhclient eth0
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# 方式二：静态地址（无 DHCP 服务器时）
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ip addr add 10.0.2.15/24 dev eth0
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ip route add default via 10.0.2.2
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echo "nameserver 10.0.2.3" > /etc/resolv.conf
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# 验证连通性
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ping -c3 10.0.2.2 # QEMU slirp 网关（永远在线，适合冒烟测试）
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ping -c3 10.0.2.3 # slirp 内建 DNS
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pacman -Sy # 联网同步包数据库
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```
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注意事项：
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- **MAC 共用**：guest virtio-net 的 MAC 与 host e1000 相同（UTSM 桥接模型，
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config 空间直接回填 host 网卡 MAC）。QEMU user-net 下 slirp 按 MAC 分配
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`10.0.2.15`；若 host Deshab 原生网络栈同时用该网卡联网，两者会抢同一
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DHCP 租约，实测时请只让一侧做 DHCP（或 host 完全不用网络）。
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- **MTU**：后端按标准 1500 MTU 转发，不支持 GSO/TSO（feature 未协商，
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guest 自动走软件分片/checksum 路径）。
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- **无中断收包**：RX 走 UTSM 周期轮询（VMX preemption timer，~1kHz）
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填充 guest RX ring 并注入 IRQ6；大流量下串口统计日志每 512 帧打印一行
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`[VNET] stat ...`（rx_filled / rx_drop_nobuf / tx_sent / tx_drop），
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可用于判断包在哪一段丢失。
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- 若 `ip link` 看不到 eth0：检查 dmesg 中 `virtio_mmio` probe 是否成功，
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以及 host 串口日志是否有 `[VNET] bound to UTSM net device 0`
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（host 侧 e1000/virtio-net DKM 驱动需先注册 netdev）。
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