Control: tag -1 + confirmed
Hi,
Axel Beckert wrote:
> > @xen-tools: I think this is because xen-tools has used the host
> > initramfs and hence has inherited some sort of hook script which insists
> > on the RAID stuff being present, which there isn't in the domU.
>
> Sounds familiar. I think I saw that one some of my DomUs, too.
Funnily the whole issue looks much more obvious when I looked at it
again today.
The issue is clearly that by default xen-tools uses the Domu0's initrd
and kernel.
Actually this gets worse if the root file system is encrypted and the
initrd waits for the according devices to show up, also in the (then
non-working) DomU. Having a dropbear SSHd in initramfs might also get
strange results.
> > I'm not sure if you would consider this a bug in xen-tools or by
> > design.
It's very likely the historical design, probably from times without
pygrub or pvgrub existed and using a kernel on the Dom0 was the common
way to boot DomUs.
> I'm not 100% sure and need to investigate the details, but there's a
> chance that this only happens if --pygrub is not used.
In the meanwhile I'm 100% sure this only happpens if the initrd is one
that is prepared for use with the Dom0.
I also think that it's very unlikely to show up if either pygrub or
pvgrub are used. If it shows up in one of these cases, it's definitely
a bug.
> Then again, even in that case the initramfs is built initially on
> the Dom0.
Which potentially could cause this issue initially because /dev/ from
the Dom0 is IIRC mounted into the chroot when building it. In that
case it should vanish once the initrd has been rebuilt once inside the
DomU.
> > You may wish to reassign this on to the initramfs generator tool
> > and/or raid packages providing the hooks.
>
> That may be one way to solve the issue, too. But I'll check first if I
> can solve that in xen-tools.
I don't think this can be solved in initramfs-tools.
I see two potential solutions, but both are rather invasive and hence
not suitable for the imminent 4.8 release:
* Switch from Dom0 kernels and initrds to pygrub or pvgrub2 as
default.
* Continue to use Dom0 kernels by default, but build dedicated initrds
for use with DomUs.
The workaround is to use --pygrub. Worked fine for me (well, except
for #921590) in the case with encrypted root file system as outlined
above.
Regards, Axel
--
,''`. | Axel Beckert <[email protected]>, https://people.debian.org/~abe/
: :' : | Debian Developer, ftp.ch.debian.org Admin
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