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Message-ID: <20080214183819.GA19846@elte.hu>
Date: Thu, 14 Feb 2008 19:38:19 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Andi Kleen <andi@...stfloor.org>
Cc: torvalds@...l.org, tglx@...utronix.de,
linux-kernel@...r.kernel.org, ying.huang@...el.com
Subject: Re: [PATCH] Fix left over EFI cache mapping problems
* Andi Kleen <andi@...stfloor.org> wrote:
> > this is indeed a bug (we change the attributes for a larger area
> > than needed), but your fix is unclean. Find below a cleaner
> > solution.
>
> You're still ignoring the other problem of set_memory_uc() not
> handling fixmap and ioremap correctly. [...]
No, we did not ignore it, and yes, you are wrong.
One thing that you miss is that the 64-bit EFI runtime has to be marked
uncacheable only if it the EFI image attribute signals an uncacheable
area:
if (!(md->attribute & EFI_MEMORY_WB))
set_memory_uc(md->virt_addr, md->num_pages);
and Linux EFI does not support device EFI runtimes. So your observation,
while correct for non-RAM 64-bit EFI images, is theoretical at the
moment and has no practical relevance.
Of course, as we've stated it numerous times, we want this all fixed up,
and we _have_ fixed it up already, but we wanted to do it properly.
Right now we've got the fixes lined up and we are waiting for a test
report and an Ack from Ying Huang. (he reported that current -git worked
just fine for him)
Also note that 64-bit EFI runtime support (the ability to execute EFI
code) is completely new - it got introduced 14 days ago. We only use
fixmaps on 64-bit EFI.
32-bit EFI is more common (but still not very common, compared to other
x86 platforms) and that is totally unaffected by secondary aliases.
(which is a complication of the 64-bit kernel)
Thanks,
Ingo
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