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Deshab-OS/CODE/linux/initramfs/init
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2026-08-09 22:20:01 +08:00

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#!/bin/sh
#
# init — Linux guest init script for UTSM dual-kernel Linux compat layer.
#
# Boot sequence (phase 2 — Arch rootfs via virtio-blk /dev/vdb):
# 1. Mount essential filesystems (proc/sys/dev)
# 2. Wait for /dev/vdb (Arch rootfs virtio-blk device) to appear
# 3. Mount /dev/vdb as ext4 at /mnt/root
# 4. Copy /dev nodes + daemon (already baked into rootfs) into /mnt/root
# 5. switch_root /mnt/root /sbin/init
# 6. Arch /sbin/init starts utsm_exec_daemon → EXEC_READY → HLT (park)
# → linux_launch() returns to UTSM
#
# Fallback (phase 1 — no rootfs, daemon in initramfs):
# - If /dev/vdb never appears, start daemon directly from initramfs.
# - If no daemon either, drop to interactive debug shell on ttyS0.
#
# The daemon runs forever, parking between requests. After switch_root,
# Arch /sbin/init owns PID 1 and must not exit.
PATH=/bin:/sbin:/usr/bin:/usr/sbin
export PATH
# Mount essential filesystems
mount -t proc none /proc 2>/dev/null
mount -t sysfs none /sys 2>/dev/null
mount -t devtmpfs none /dev 2>/dev/null
echo "[utsm-linux] init started"
echo "[utsm-linux] kernel: $(uname -r)"
# Verify /dev/utsm exists (driver is built-in, should be auto-created)
if [ ! -e /dev/utsm ]; then
echo "[utsm-linux] WARNING: /dev/utsm not found — UTSM driver not loaded"
fi
# ===== Phase 2: switch_root to Arch rootfs on /dev/vdb =====
# The rootfs is exposed as a memory-backed virtio-blk device (GPA 0xF4002000,
# IRQ7). Wait up to ~5s for the kernel to discover it via devtmpfs.
echo "[utsm-linux] waiting for /dev/vdb (Arch rootfs)..."
VDB_OK=0
i=0
while [ $i -lt 50 ]; do
if [ -b /dev/vdb ]; then
VDB_OK=1
break
fi
# 100ms sleep (busybox sleep supports fractional seconds)
sleep 0.1
i=$((i + 1))
done
if [ $VDB_OK -eq 1 ]; then
echo "[utsm-linux] /dev/vdb found, attempting ext4 mount..."
mkdir -p /mnt/root
# Try ext4 (preferred); fall back to ext2 if ext4 module absent.
if mount -t ext4 -o ro /dev/vdb /mnt/root 2>/dev/null || \
mount -t ext2 -o ro /dev/vdb /mnt/root 2>/dev/null; then
echo "[utsm-linux] rootfs mounted, verifying /sbin/init..."
if [ -x /mnt/root/sbin/init ]; then
echo "[utsm-linux] switch_root → Arch /sbin/init"
# Move dev/proc/sys into new root so the Arch init can re-mount them.
mount --move /dev /mnt/root/dev 2>/dev/null
mount --move /proc /mnt/root/proc 2>/dev/null
mount --move /sys /mnt/root/sys 2>/dev/null
# ===== VSCode Phase 4: overlay 持久化(/dev/vdc extra-rootfs 可写卷)=====
# rootfs 以 ro 挂载;/opt(VSCode 安装位置)、/home、/root 通过
# overlayfs 获得可写层,upperdir/workdir 落在 /dev/vdc(virtio-blk
# slot6 可写后端,内容跨启动持久)。vdc 缺失时保持 ro,安全降级。
if [ -b /dev/vdc ]; then
echo "[utsm-linux] /dev/vdc found, setting up overlay persistence..."
modprobe overlay 2>/dev/null
mkdir -p /mnt/persist
if mount -t ext4 -o rw /dev/vdc /mnt/persist 2>/dev/null; then
for d in opt home root; do
mkdir -p /mnt/persist/overlay/$d/upper \
/mnt/persist/overlay/$d/work \
/mnt/root/$d
if mount -t overlay overlay \
-o lowerdir=/mnt/root/$d,upperdir=/mnt/persist/overlay/$d/upper,workdir=/mnt/persist/overlay/$d/work \
/mnt/root/$d 2>/dev/null; then
echo "[utsm-linux] overlay: /$d rw (persist)"
else
echo "[utsm-linux] WARNING: overlay /$d failed (stays ro)"
fi
done
# persist 卷搬进新 root,switch_root 后可在 /mnt/persist 访问
mkdir -p /mnt/root/mnt/persist
mount --move /mnt/persist /mnt/root/mnt/persist 2>/dev/null
else
echo "[utsm-linux] WARNING: /dev/vdc mount failed (no persistence)"
fi
fi
exec switch_root /mnt/root /sbin/init
# switch_root does not return
else
echo "[utsm-linux] WARNING: /mnt/root/sbin/init missing, not switching"
umount /mnt/root 2>/dev/null
fi
else
echo "[utsm-linux] WARNING: ext4/ext2 mount of /dev/vdb failed"
echo "[utsm-linux] available block devices:"
ls -l /dev/vd* /dev/sd* 2>/dev/null
fi
else
echo "[utsm-linux] /dev/vdb not found after 5s — phase-1 fallback"
fi
# ===== Fallback: daemon directly from initramfs (phase 1) =====
if [ -x /bin/utsm_exec_daemon ]; then
echo "[utsm-linux] starting utsm_exec_daemon from initramfs..."
/bin/utsm_exec_daemon &
DAEMON_PID=$!
echo "[utsm-linux] daemon PID=$DAEMON_PID"
# init must not exit — sleep forever to keep the kernel happy.
echo "[utsm-linux] init: daemon running, entering idle hold"
while true; do
sleep 3600
done
fi
# ===== Last resort: interactive debug shell on ttyS0 =====
# No daemon and no rootfs — bring-up smoke test only.
echo "[utsm-linux] WARNING: no daemon, no rootfs — starting interactive debug shell on ttyS0"
exec /bin/setsid /bin/cttyhack /bin/sh