[Bug 14908] Re: swsusp fails after automatic kernel upgrade

[Matt Zimmerman]

On Fri, Oct 20, 2006 at 08:57:21PM -0400, Ben Collins wrote:
> On Sat, 2006-10-21 at 00:07 +0000, Matt Zimmerman wrote:
> > Ben, please arrange for future kernels to drop a file or such so that we
> > can test its timestamp against the uptime of the system to determine
> > whether the kernel has been upgraded since the last reboot (and refuse
> > to hibernate in this case).
> 
> I thought we had setup the /proc/version_signature file for this very
> reason?

I don't think that's quite enough, since it's non-trivial to query for the
version of the kernel which will be used on the next boot in order to
compare with this.  The test which I think gives us the best combination of
accuracy and simplicity is "has a new kernel been installed since the last
boot?".  That will only be wrong under special and unusual circumstances
(user installing a new non-default kernel).

> Also, it's very easy to test for /var/run/reboot-required, which shows
> that some update of the system is requiring a reboot. The largest user
> of this file is the kernel. I would be willing to bet that other users
> would also be grounds for not hibernating.
>
> So if the hibernation scripts test for /var/run/reboot-required, they
> could use this as a means for deciding not to hibernate.

Unfortunately, several other components use this as well.  initscripts,
udev, dbus, hal, etc., and we don't want to disable hibernation
unnecessarily in those cases (especially for users of the development
branch where those may change often).

-- 
 - mdz

-- 
swsusp fails after automatic kernel upgrade
https://launchpad.net/bugs/14908