To be clearer about what is being discussed here, this is the proposed menuentry for the current grub.cfg from the pastebin:
Code:
default=0
timeout=5
menuentry 'znix' {
insmod gzio
insmod part_gpt
echo 'Loading znix kernel'
linux /boot/bzImage init=/bin/init acpi=off
echo 'Loading initramfs'
initrd /boot/initramfs.cpio.gz
}
Here are some thoughts.
Traditionally init is run from /sbin/init, not /bin/init, though in modern merged filesystems of these executable directories, it's /usr/sbin and /usr/bin. That's not to say that one can't make peculiar changes to conventions, but what would be the point?
/usr/sbin/init in modern systemd systems is a link to /lib/systemd/systemd. In SysVinit systems, init is configured in /etc/inittab which determines the runlevel to start the system which starts up a number of programs from scripts usually in the subdirectories of /etc/rc.d. Which init system is being proposed here?
If the system is to start with a manual mounting of the rootfs, then one can use the kernel option /bin/sh, which will start a root shell on boot, but won't load the initramfs. Rather, /bin/sh, with a rw option, can run from the rootfs and use the programs in place there. This approach is usually used when the user wants to get access to the system to correct something like changing a password or altering a config file.
If the kernel configuration puts all the relevant modules for the system inside itself, the initramfs can be omitted altogether.
If it's of interest, inside the initramfs on this machine, running debian, the init command is actually just "init" with /usr/sbin/init being empty.
Code:
lsinitramfs -l /boot/initrd.img-6.5.0-4-amd64 | grep init
-rw-r--r-- 1 root root 1583 Jun 21 2022 conf/initramfs.conf
-rwxr-xr-x 1 root root 6556 Apr 11 2022 init
drwxr-xr-x 2 root root 0 Nov 19 11:43 scripts/init-bottom
-rw-r--r-- 1 root root 77 Nov 19 11:43 scripts/init-bottom/ORDER
-rwxr-xr-x 1 root root 611 Sep 21 00:44 scripts/init-bottom/udev
drwxr-xr-x 2 root root 0 Nov 19 11:43 scripts/init-top
-rw-r--r-- 1 root root 314 Nov 19 11:43 scripts/init-top/ORDER
-rwxr-xr-x 1 root root 396 Apr 11 2022 scripts/init-top/all_generic_ide
-rwxr-xr-x 1 root root 296 Sep 1 2020 scripts/init-top/blacklist
-rwxr-xr-x 1 root root 167 Sep 1 2020 scripts/init-top/keymap
-rwxr-xr-x 1 root root 568 Sep 21 00:44 scripts/init-top/udev
-rw-r--r-- 1 root root 2048 Jul 5 00:44 usr/lib/firmware/ene-ub6250/ms_init.bin
-rw-r--r-- 1 root root 2048 Jul 5 00:44 usr/lib/firmware/ene-ub6250/sd_init1.bin
-rw-r--r-- 1 root root 2048 Jul 5 00:44 usr/lib/firmware/ene-ub6250/sd_init2.bin
-rw-r--r-- 1 root root 68331 Nov 3 15:15 usr/lib/modules/6.5.0-4-amd64/kernel/drivers/scsi/initio.ko
-rwxr-xr-x 257 root root 0 Oct 7 03:07 usr/sbin/run-init
-rwxr-xr-x 257 root root 0 Oct 7 03:07 usr/sbin/init
Rob Landley is a wiz on these matters, e.g.
https://www.landley.net/writing/rootfs-howto.html, so it may be worth following up his articles from his sites and in the kernel docs.
