commit: 0228db0a73c2ee2923371459de5a95ae9fdf905b
parent 3cfcae8287eb4b6d47fce9d642164011e2c37e17
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date: Wed, 24 Dec 2025 00:46:31 +0100
make-img.sh: Add
Diffstat:
| A | make-img.sh | 49 | +++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 49 insertions(+), 0 deletions(-)
diff --git a/make-img.sh b/make-img.sh
@@ -0,0 +1,49 @@
+#!/bin/sh
+
+set -ex -o pipefail || exit 1
+
+SYSLINUX=/usr/share/syslinux
+KERNEL=/mnt/alpine/boot/vmlinuz-lts
+INITRD=bootstrap-initrd/x86_64+extras.cpio.gz
+
+ALPINE_ARCH=x86_64 ./make-initrd.sh
+
+FAT_PARTSZ=$(wc -c "$INITRD" "$KERNEL" | grep total | cut -f1 -d' ')
+
+# Add 25% for inodes, syslinux, …
+FAT_PARTSZ="$(printf '%s 1.25 * 512 / 512 * p\n' "${FAT_PARTSZ}" | dc)"
+
+rm -f bootstrap-initrd/x86_64.fat
+truncate -s "${FAT_PARTSZ}" bootstrap-initrd/x86_64.fat
+
+# FAT16 because otherwise syslinux throws an error:
+# + syslinux -i bootstrap-initrd/x86_64.fat
+# syslinux: zero FAT sectors (FAT12/16)
+mkfs.fat -D 0x80 -F16 bootstrap-initrd/x86_64.fat
+
+mcopy -i bootstrap-initrd/x86_64.fat "$KERNEL" ::vmlinuz
+mcopy -i bootstrap-initrd/x86_64.fat "$INITRD" ::x86_64.cpio.gz
+
+cat >bootstrap-initrd/x86_64.syslinux.cfg <<'EOF'
+DEFAULT linux
+LABEL linux
+ KERNEL vmlinuz
+ INITRD x86_64.cpio.gz
+EOF
+
+mcopy -i bootstrap-initrd/x86_64.fat bootstrap-initrd/x86_64.syslinux.cfg ::syslinux.cfg
+
+syslinux -i bootstrap-initrd/x86_64.fat
+
+mdir -i bootstrap-initrd/x86_64.fat -a
+
+rm -f bootstrap-initrd/x86_64.img
+truncate -s "$((2048 + ${FAT_PARTSZ}))" bootstrap-initrd/x86_64.img
+
+sfdisk bootstrap-initrd/x86_64.img <<'EOF'
+label: mbr
+start=2048, size=+, type=0x06, bootable
+EOF
+
+dd if="${SYSLINUX}/mbr.bin" conv=notrunc of=bootstrap-initrd/x86_64.img
+dd if=bootstrap-initrd/x86_64.fat conv=notrunc of=bootstrap-initrd/x86_64.img seek=2048 status=progress
