Martin Steigerwald said on Fri, 01 Dec 2023 16:59:40 +0100

>Steve Litt - 01.12.23, 07:22:32 CET:
>> >> >Are you saying that as long as the system is booting using an
>> >> >initramfs, which mine does since it usesa stock kernel, that
>> >> >having a separate partition for /usr will not be an issue, even
>> >> >after all of this usr-merge garbage goes into effect?
>> >>
>> >> The opposite. I'm saying that a merged system MUST HAVE an
>> >> initramfs in order to correctly boot, unless the kernel has the
>> >> driver for your boot disk compiled in.
>> >
>> >Isn't that true of an unmerged system, too?
>>
>> Yes! :-)
>
>Ah interesting. I thought an unmerged system would be able to boot up
>with stuff from /bin, /sbin, /lib and other top level directories up
>to the point to be able to mount /usr without the help of mounting
>within initramfs. At least with sysvinit, openrc or runit. AFAIR
>Systemd required mounting a separate /usr in initramfs since a long
>time.

Martin, we're both right and wrong :-)

If the driver for the root partition is compiled into the kernel, then
yes, the stuff in /sbin can enable you to bootsrap up to mounting /usr,
even if the partition mounted to /usr is formatted as "Tommy's perfect
snapshotting filesystem" or whatever. But the kernel must be capable of
mounting the root partition to remove the need for initramfs. AND,
there must be /sbin and its kin as directories on the root partition,
not mounted entities.

Unfortunately, a lot of distros don't even compile the Ext4 drivers
into the kernel. Without the Ext4 driver compiled into the kernel, you
can't mount the root partition to read what to do next.

If I had my way, people would compile Linux kernels with drivers for
Ext4 and a couple of the most popular other filesystems, and would have
software on an on-root, unmounted unsymlinked /sbin and its relatives.
You know, the way it was in 1998 :-(

SteveT

Steve Litt

Autumn 2023 featured book: Rapid Learning for the 21st Century
http://www.troubleshooters.com/rl21