fix(ci): save kernel cache immediately after build and fix initramfs symlinks

- Split actions/cache into restore + save to cache kernel right after
  build, so failures in later steps don't waste the build
- Fix build_initramfs.sh to use inline relative symlink creation instead
  of gen_links.sh which uses absolute paths

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Charliechen114514

.github/workflows/ci.yml

@@ -241,9 +241,9 @@ jobs:
             echo "cross=arm-none-linux-gnueabihf-" >> "$GITHUB_OUTPUT"
           fi
 
-      - name: Cache Linux kernel
+      - name: Restore Linux kernel cache
         id: cache-kernel
-        uses: actions/cache@v4
+        uses: actions/cache/restore@v4
         with:
           path: |
             third_party/linux/${{ steps.kernel.outputs.image }}
@@ -258,6 +258,16 @@ jobs:
           make ARCH=${{ steps.kernel.outputs.arch }} CROSS_COMPILE=${{ steps.kernel.outputs.cross }} ${{ steps.kernel.outputs.defconfig }}
           make ARCH=${{ steps.kernel.outputs.arch }} CROSS_COMPILE=${{ steps.kernel.outputs.cross }} -j$(nproc)
 
+      - name: Save Linux kernel cache
+        if: steps.cache-kernel.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            third_party/linux/${{ steps.kernel.outputs.image }}
+            third_party/linux/.config
+            ${{ matrix.target == 'armhf' && 'third_party/linux/arch/arm/boot/dts/arm/vexpress-v2p-ca9.dtb' || '' }}
+          key: linux-kernel-${{ matrix.target }}-${{ hashFiles('third_party/linux/Makefile') }}-${{ steps.kernel.outputs.defconfig }}
+
 
       - name: Build initramfs (CFBox only, no busybox)
         run: |

scripts/build_initramfs.sh

@@ -70,30 +70,24 @@ case "$arch" in
     *)       qemu_bin="qemu-$arch-static" ;;
 esac
 
-# Try running cfbox directly; if it fails (foreign arch), use QEMU wrapper
+# Determine how to run the cross-compiled cfbox --list
+# Symlinks must use relative paths (cfbox, not absolute) for the initramfs.
 if "$initramfs/bin/cfbox" --list >/dev/null 2>&1; then
-    "$project_dir/scripts/gen_links.sh" "$initramfs/bin"
+    list_cmd="$initramfs/bin/cfbox"
+elif command -v "$qemu_bin" &>/dev/null; then
+    list_cmd="$qemu_bin $initramfs/bin/cfbox"
 else
-    if ! command -v "$qemu_bin" &>/dev/null; then
-        echo "ERROR: $qemu_bin needed to run cross-compiled cfbox --list"
-        exit 1
-    fi
-    # Create wrapper just for `--list` invocation
-    qemu_wrapper="$(mktemp /tmp/cfbox-genlinks-XXXXXX.sh)"
-    echo "#!/bin/sh" > "$qemu_wrapper"
-    echo "exec $qemu_bin $initramfs/bin/cfbox \"\$@\"" >> "$qemu_wrapper"
-    chmod +x "$qemu_wrapper"
-
-    # Get applet list via QEMU wrapper, create symlinks to the real binary
-    while IFS= read -r line; do
-        name=$(echo "$line" | awk '{print $1}')
-        [[ -z "$name" ]] && continue
-        ln -sf cfbox "$initramfs/bin/$name"
-        echo "  linked $name"
-    done < <("$qemu_wrapper" --list)
-    rm -f "$qemu_wrapper"
+    echo "ERROR: $qemu_bin needed to run cross-compiled cfbox --list"
+    exit 1
 fi
 
+while IFS= read -r line; do
+    name=$(echo "$line" | awk '{print $1}')
+    [[ -z "$name" ]] && continue
+    ln -sf cfbox "$initramfs/bin/$name"
+    echo "  linked $name"
+done < <($list_cmd --list)
+
 # Create /init symlink — the kernel executes this first.
 # CFBox's init applet will detect PID 1 and mount filesystems automatically.
 ln -sf bin/cfbox "$initramfs/init"