From: Matthew Garrett <mjg59@srcf.ucam.org>
To: rwright@hp.com
Cc: linux-kernel@vger.kernel.org, tmac@hp.com, hpa@zytor.com
Subject: Re: [PATCH RFC] function probe_roms accessing improper addresses
Date: Tue, 23 Oct 2012 17:27:18 +0100 [thread overview]
Message-ID: <20121023162718.GA32085@srcf.ucam.org> (raw)
In-Reply-To: <201210231605.q9NG51KW022791@filesys1.fc.hp.com>
On Tue, Oct 23, 2012 at 10:05:01AM -0600, Randy Wright wrote:
> On the first: one way to be compliant with such a requirement would be
> to design systems that implement softfail in this particular region.
> What about a system that hardfails, but on which the resulting machine
> check can be handled by the kernel machine check handler? Would
> appropriate re-ordering of the kernel initialization code to support
> such systems be acceptable?
Good question. I don't maintain that code, so I can't really answer
it...
> Also, let me mention a possible amendment to your first idea: what if
> the mandate that probing be supported were qualified by some attribute
> that could be indicated in the UEFI environment? For example: instead
> of just a hole in the UEFI memory map, what if this range was
> specifically present and typed as EfiUnusableMemory? Another idea for
> UEFI systems - but one requiring a UEFI specification change - might be
> adding a UEFI variable that if present, indicates any area not
> explicitly included and typed in the UEFI memory map (including the
> legacy adapter region) must be explicitly avoided by an OS.
Yeah, I think if it were marked unusable we could probably justify
staying away from it.
> > 2) Don't call probe_roms() by default, but leave it up to the graphics
> > drivers. If they can get the rom by any other means then don't call it.
>
> One the second idea: there are a quite a lot of video drivers in the kernel
> source tree. Do you have a suggestion for how to evaluate which ones
> rely on the setup performed by probe_roms?
Realistically - intel, radeon and nouveau. Basically, anything that
calls pci_map_rom() and is under drivers/gpu/drm. I'll look into a patch
that does that.
--
Matthew Garrett | mjg59@srcf.ucam.org
next prev parent reply other threads:[~2012-10-23 16:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <jQZho-4fF-13@gated-at.bofh.it>
[not found] ` <jSWfn-7B6-3@gated-at.bofh.it>
2012-10-19 15:20 ` [PATCH RFC] function probe_roms accessing improper addresses Randy Wright
2012-10-19 15:30 ` Matthew Garrett
2012-10-19 15:37 ` H. Peter Anvin
2012-10-23 16:05 ` Randy Wright
2012-10-23 16:27 ` Matthew Garrett [this message]
2012-10-04 19:22 [PATCH RFC] function probe_roms accessing improper addresses on UEFI systems Matthew Garrett
2012-10-10 4:31 ` [PATCH RFC] function probe_roms accessing improper addresses Randy Wright
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