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setup erofs for tiny rootfs! #68

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Merged
adeebshihadeh merged 1 commit into from
Mar 28, 2026
+43 −1
Merged

setup erofs for tiny rootfs! #68

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5 changes: 5 additions & 0 deletions kernel/configs/vamos.config
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Original file line number Diff line number Diff line change
Expand Up @@ -84,5 +84,10 @@ CONFIG_TOUCHSCREEN_S6SY761=y
CONFIG_EXPERT=y
CONFIG_GPIO_SYSFS=y

# EROFS
CONFIG_EROFS_FS=y
CONFIG_EROFS_FS_ZIP=y
CONFIG_EROFS_FS_ZIP_LZ4=y

# Misc
CONFIG_LOCALVERSION_AUTO=n
16 changes: 15 additions & 1 deletion tools/build/Dockerfile.builder
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Expand Up @@ -19,10 +19,24 @@ RUN apk add --no-cache \
git \
libcap \
linux-headers \
lz4-dev \
openssl \
openssl-dev \
perl \
python3
python3 \
util-linux-dev \
xz-dev

# Build erofs-utils from source (not packaged in Alpine)
RUN git clone https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git /tmp/erofs-utils \
&& cd /tmp/erofs-utils \
&& git checkout v1.8.5 \
&& apk add --no-cache autoconf automake libtool \
&& autoreconf -fi \
&& ./configure --enable-lz4 --enable-lzma --disable-fuse \
&& make -j$(nproc) \
&& make install \
&& rm -rf /tmp/erofs-utils

# Cross-compiler for x86_64 hosts building aarch64 kernel
# gcc-aarch64-none-elf is bare-metal but works for kernel (freestanding code)
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23 changes: 23 additions & 0 deletions tools/build/build_system.sh
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Expand Up @@ -129,6 +129,17 @@ MOUNT_CONTAINER_ID="$MOUNT_CONTAINER_ID" ROOTFS_DIR="$ROOTFS_DIR" \
ROOTFS_IMAGE="$ROOTFS_IMAGE" OUTPUT_DIR="$OUTPUT_DIR" \
"$DIR/vamos" profile

# Build EROFS image (before unmount, while rootfs is still mounted)
EROFS_IMAGE="$BUILD_DIR/system.erofs.img"
OUT_EROFS_IMAGE="$OUTPUT_DIR/system.erofs.img"
echo "Building EROFS image (LZ4HC, 64K clusters)"
exec_as_root mkfs.erofs \
-zlz4hc,12 \
-C65536 \
-T0 \
--all-root \
"$EROFS_IMAGE" "$ROOTFS_DIR"

# Unmount image
echo "Unmount filesystem"
exec_as_root umount -l "$ROOTFS_DIR"
Expand All @@ -137,6 +148,9 @@ exec_as_root umount -l "$ROOTFS_DIR"
echo "Sparsifying system image"
exec_as_user img2simg "$ROOTFS_IMAGE" "$OUT_IMAGE"

# Copy EROFS image to output
cp "$EROFS_IMAGE" "$OUT_EROFS_IMAGE"

# Patch sparse image size into profile JSON
SPARSE_SIZE=$(stat -c%s "$OUT_IMAGE" 2>/dev/null || stat -f%z "$OUT_IMAGE")
if command -v jq &>/dev/null; then
Expand All @@ -145,4 +159,13 @@ if command -v jq &>/dev/null; then
mv "$OUTPUT_DIR/rootfs-profile.json.tmp" "$OUTPUT_DIR/rootfs-profile.json"
fi

# Size comparison
EXT4_SPARSE_SIZE=$(stat -c%s "$OUT_IMAGE" 2>/dev/null || stat -f%z "$OUT_IMAGE")
EROFS_SIZE=$(stat -c%s "$OUT_EROFS_IMAGE" 2>/dev/null || stat -f%z "$OUT_EROFS_IMAGE")
echo ""
echo "=== Image size comparison ==="
echo "ext4 (sparse): $(numfmt --to=iec-i --suffix=B "$EXT4_SPARSE_SIZE") ($EXT4_SPARSE_SIZE bytes)"
echo "EROFS (LZ4HC): $(numfmt --to=iec-i --suffix=B "$EROFS_SIZE") ($EROFS_SIZE bytes)"
echo ""

echo "Done!"
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