Re: Bug#915880: lvm2: Dependency on liblz4-1 causes /sbin binaries to depend on /usr/lib libraries
On Tue, 2018-12-11 at 08:27 +0200, Per Lundberg wrote:
> Hi Adrian,
>
> Quoting the page you linked to:
>
> > This section only applies to systems using a custom kernel, where
> /usr is on a separate mount point from /. If you use the kernel
> packages provided by Debian, you are unaffected by this issue.
>
> >From what I can tell in this text, keeping /usr on a separate mount
> point _is_ indeed supported (as long as you are using a stock kernel
> and a proper initramfs generator) - and as noted in my followup email,
> installing Buster on a /usr volume works fine. Also, the Debian
> installer provides /usr as an option when partitioning your disk. If
> indeed maintaining /usr on a separate partition is completely
> unsupported (which you indicate),
A separate /usr is supported with a custom kernel if and only if you
arrange for it to be mounted by the initramfs, you cannot (any longer)
rely on / to contain everything necessary to mount /usr. I think the
remainder of the section you partly quoted above makes this clear, if
you disagree perhaps you could suggest an improvement to the wording:
Mounting of /usr using only tools found in / is no longer supported.
This has only worked for a few specific configurations in the past,
and now they are explicitly unsupported.
This means that for stretch all systems where /usr is a separate
partition need to use an initramfs generator that will mount /usr.
All initramfs generators in stretch do so.
The note you quoted is simply saying that the kernel packages in
Debian, together with the initramfs generators, meet this requirement
so if you are using those you need not worry about the specifics.
I don't know if any of the above applies to Ubuntu (where you've
observed an actual failure), so if you have found a case where the
initramfs generator is not doing the right thing for that distro you
should open a bug with them.
Ian.
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