Re: [PATCH] dmi_check_system can generate Warnings when no DMItable is present

From: Ingo Molnar
Date: Fri Oct 23 2009 - 13:04:40 EST



* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> On 10/23/09 08:30, Ingo Molnar wrote:
> >> Ingo mentioned that the returning mechanism your adding was left out
> >> intentionally to catch this error, so I don't think your original
> >> patch could be included ..
> >>
> > Yes. That mechanism found a real bug here.
> >
> > Calling the DMI code too early (when the strings are still empty)
> > can cause silent failures: we wont crash but we might miss to act on
> > DMI quirks.
>
> Yes. There's nothing preventing the DMI subsystem from being
> initialized under Xen; in fact we rely on it in a dom0 kernel (which
> does have access to the DMI tables). I don't know what the underlying
> bug in the original report is, but there's more to it than failing to
> init DMI.

yeah. It's probably some init ordering problem - some version of Xen
calling into the DMI code too early. It probably doesnt even matter in
practice as we rarely rely on DMI details in Xen guests, right?

Ingo
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