Record networking and DMA development progress

Add the current OS source tree, build scripts, system image layout, and development notes covering DMA page allocation, e1000 bring-up, net API dispatch, and DHCP work in progress.

CODE/UTSM/kernel/block.c

@@ -0,0 +1,58 @@
+#include <utsm/block.h>
+#include <utsm/log.h>
+
+static dkm_block_device_desc g_devices[DKM_BLOCK_MAX_DEVICES];
+static u32 g_device_count;
+
+void block_init(void) {
+    g_device_count = 0;
+    log_info("[BLOCK] registry init");
+}
+
+static int block_register_device_impl(const dkm_block_device_desc *desc) {
+    if (!desc || !desc->read || !desc->sector_size) return -1;
+    if (g_device_count >= DKM_BLOCK_MAX_DEVICES) return -2;
+
+    u32 index = g_device_count++;
+    g_devices[index] = *desc;
+
+    log_info("[BLOCK] device registered");
+    if (desc->name) log_info(desc->name);
+    log_hex64("[BLOCK] index=", index);
+    log_hex64("[BLOCK] sector_size=", desc->sector_size);
+    log_hex64("[BLOCK] sector_count=", desc->sector_count);
+    return (int)index;
+}
+
+static u32 block_device_count_impl(void) {
+    return g_device_count;
+}
+
+static int block_read_impl(u32 index, u64 lba, u32 count, void *buffer) {
+    if (index >= g_device_count || !buffer || count == 0) return -1;
+    dkm_block_device_desc *dev = &g_devices[index];
+    if (!dev->read) return -2;
+    return dev->read(dev->ctx, lba, count, buffer);
+}
+
+static u64 block_sector_size_impl(u32 index) {
+    if (index >= g_device_count) return 0;
+    return g_devices[index].sector_size;
+}
+
+static const char *block_device_name_impl(u32 index) {
+    if (index >= g_device_count) return 0;
+    return g_devices[index].name;
+}
+
+static const dkm_block_api g_block_api = {
+    .register_device = block_register_device_impl,
+    .device_count = block_device_count_impl,
+    .read = block_read_impl,
+    .sector_size = block_sector_size_impl,
+    .device_name = block_device_name_impl
+};
+
+const dkm_block_api *block_get_api(void) {
+    return &g_block_api;
+}