Re: Meltdown fix for wheezy-backports
On Tue, 23 Jan 2018 at 10:14:12 -0600, Xan Charbonnet wrote:
> I can't seem to find it now, but I believe somewhere official there is (or
> was at one time?) a diagram showing how LTS would allow skipping stable
> versions: for example, going directly from Wheezy to Stretch, and stretch to
> Bullseye, skipping Jessie and Buster.
Debian does not support skipping a version. If you want to upgrade from
wheezy to stretch, you have to upgrade from wheezy to jessie, and then
from jessie to stretch, with at least one reboot in between (because
packages in version n are allowed to assume that they run on at least the
kernel from version n-1). You can do both upgrades during the same period
of downtime if you want, although I wouldn't necessarily advise it!
We run into enough difficulties with supporting upgrades across a 2 year
gap (working around bugs in 2-year-old packages that can no longer be
changed) that I find it unlikely for there to be project consensus that
we want to aim to support single-step upgrades across a 4 year gap.
You might be thinking of Ubuntu, where upgrading from one LTS release
to the next, skipping the intermediate 6-monthly development releases,
is supported. That's also an upgrade across a 2 year gap.
> Surely there are advantages to having a true
> backport, like guaranteeing that device enumeration and naming stay the
> same, the kernel would be compiled by the same compiler as the rest of the
> system, any custom/non-standard kernel modules would have to be re-thought,
> there are probably a dozen other reasons I don't even know about.
To the best of my knowledge, nobody guarantees that device enumeration
and naming in backports kernels are the same as in the original kernels
of the target release. The changelog of the kernel in stretch-backports
certainly doesn't mention any such change.
Your point about the compiler is valid: backported kernels do get
compiled with the target release's compiler (although I don't know how
long that will remain true if Spectre mitigations need new compiler
development).
I don't think custom/non-standard kernel modules have any particular
guarantees, although major out-of-tree kernel modules like
nvidia-graphics-drivers do get backported by their maintainers.
smcv
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