Make Alpine Linux boot dance to your tune (Part 1) - Everything in usr folder

Method 1 (DISK - RAM boot)

1. Create a ram based basic bootable disk. ^{[2] [3] [4] [5]}

Whenever I read about /usr merge logics and the need for it, I have this thinking always coming up as what is actual reason to move to /usr, now I think having everything in /usr is more important than /bin /usr/bin ..etc merged

Here a sidekick solution - somewhat non-standard approach with modified initramfs code.

Create folders in /usr/system

1. Create dir in /usr/system

(1)
/
`-- usr
    `-- system
        |-- bin
        |-- etc
        |-- lib
        `-- sbin

Link or bind these folders

2. Link or bind these folder as in 1 above on /bin, /sbin, /lib, /etc

(2)
/
|-- bin -> /usr/system/bin
|-- etc -> /usr/system/etc
|-- lib -> /usr/system/lib
|-- sbin -> /usr/system/sbin
`-- usr
    `-- system
        |-- bin
        |-- etc
        |-- lib
        `-- sbin

Modify initramfs scripts

3. init

879a880,889
> # Move all binary installations + /etc to /usr/system/ and symlink to /
> SDIR="$sysroot/usr/system"; mkdir -p $SDIR
> S="bin sbin lib etc"; _PD=$PWD
> for d in $S; do
> 	$MOCK mkdir -p $sysroot/$d
> 	# Careful as only relative paths would work
> 	$MOCK mv "$sysroot/$d" $SDIR && cd $sysroot && ln -s "usr/system/$d" ./
> done
> cd $_PD
> 

patch init init.patch
sha1sum init.patch init init.patched

 1c973f9ce017941df7ce59785709d7c7ff189d6d  init.patch
 57ef7d9bc90b9afd550669d5beacb26fc2f1a97c  init         (orig, VERSION=3.12.0-r0)
 96cc1a0ea8a33ea280bdfee4462a4de165895057  init.patched (modified)

Quirks

vi /etc/local.d/00.bindetc.start

 #!/bin/sh
 cd /; rm -f etc && mkdir /etc && mount -o bind /usr/system/etc /etc

chmod +x /etc/local.d/00.bindetc.start
sh /etc/local.d/00.bindetc.start # run it if already booted in modified initramfs-lts
rc-update add local
lbu ci

GOALS ACHIEVED

1. With folder structure as 2 above, everything would get installed in /usr.
2. Modified initramfs scripts, that can be booted to a folder structure as 2 above.

Things not there yet

Full /usr merged, as envisioned in https://alpinelinux.org/posts/2025-10-01-usr-merge.html

Possibilities

• Setup to start/migrate gradually to a true usr-merge.
  • Hard-coded exceptions like - /bin/sh, musl libs, firmwares, can still be left to be handled by /usr/system folders.
• Experiment with this method and come-up with a method/code to make (before official usr-merge gets fully implemented).
  1. /usr read-only(squashfs) (user'blobs merrymium ~HP)
  2. or encrypted (user'merry encryptium ~HP)

Author

V.Krishn

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