[systemd-devel] [PATCH] fstab-generator: introduce rd.weak_sysroot to bypass failures in sysroot.mount

[WANG Chao]

On 07/30/13 at 02:05pm, Tom Gundersen wrote:
> On Tue, Jul 30, 2013 at 1:53 PM, WANG Chao <chaowang at redhat.com> wrote:
> > If specified kernel command line rd.weak_sysroot, fstab-generate will
> > generate a weaker version of sysroot.mount:
> >  - It's not required by initrd-root-fs.target.
> >  - It's not before initrd-root-fs.target.
> >
> > So that failure in the weaker sysroot.mount will not fail
> > initrd-root-fs.target. And systemd will try continue rather than
> > entering isolated emergency mode.
> 
> Can you give an example case where this is useful? I.e., what is the
> setup and how is boot supposed to succeed with a failing sysroot?

Some initrd that using systemd, isn't serverd as a general purpose boot
initrd.

In case of kdump, 2nd kernel initrd is used to mount non-root local/remote
filesystem and dump vmcore there. The kdump script is running right
before switch-root and will reboot after saving vmcore.

So mounting sysroot isn't quite justified in this case.  But it's still
acceptable (since it's readonly mount), as long as it's not keeping
systemd from reaching initrd.target (so kdump script can run later).

Thanks
WANG Chao