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Message-Id: <1203043953.30010.14.camel@caritas-dev.intel.com>
Date: Fri, 15 Feb 2008 10:52:33 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: Andi Kleen <andi@...stfloor.org>, torvalds@...l.org,
tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix left over EFI cache mapping problems
On Thu, 2008-02-14 at 19:38 +0100, Ingo Molnar wrote:
> * 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.
On my test machine, there is EFI runtime memory area with EFI_MEMORY_UC
attribute. The following is cut from the dmesg:
EFI: mem75: type=4, attr=0xf, range=[0x000000007f4ff000-0x000000007f500000) (0MB)
EFI: mem76: type=11, attr=0x8000000000000001, range=[0x00000000fed1c000-0x00000000fed20000) (0MB)
EFI: mem77: type=11, attr=0x8000000000000001, range=[0x00000000fffb0000-0x00000000fffb4000) (0MB)
Where:
attr is md->attribute,
#define EFI_MEMORY_RUNTIME 0x8000000000000000
#define EFI_MEMORY_UC 0x0000000000000001
But because end_pfn_map contains the above UC memory area, efi_ioremap()
is not used on EFI 64.
Best Regards,
Huang Ying
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