prepare for erofs

Dockerfile

@@ -9,8 +9,7 @@ run --mount=type=cache,id=novit-rs,target=/usr/local/cargo/registry \
     RUSTFLAGS="-C target-feature=-crt-static" cargo install --path . --root /dist
 
 # ------------------------------------------------------------------------
-from alpine:3.23.4 as initrd
-run apk add zstd lz4
+from alpine:3.23.4 as system
 
 workdir /system
 
@@ -31,9 +30,26 @@ run mkdir -p bin run var/log; cd bin && for cmd in init-version init-connect boo
 # check viability
 run chroot . init-version
 
-run find * |cpio -H newc -oF /initrd
+# ------------------------------------------------------------------------
+from alpine:3.23.4 as initrd
+
+copy --from=system /system /system
+run cd /system && find * |cpio -H newc -oF /initrd
+
+# ------------------------------------------------------------------------
+from debian:stable-backports as initramfs
+run apt update && apt install -y erofs-utils
+
+copy --from=system /system /system
+run mkfs.erofs \
+  -z lzma -C131072 -Efragments,ztailpacking \
+  -T0 --all-time --ignore-mtime \
+  /initramfs /system
 
 # ------------------------------------------------------------------------
 from alpine:3.23.4
-copy --from=initrd /initrd /
+copy --from=initrd /initrd /initrd
 entrypoint ["base64","/initrd"]
+
+#copy --from=initramfs /initramfs /
+#entrypoint ["base64","/initramfs"]