linux-kernel - Re: [PATCH v3] x86, efi: Calling __pa() with an ioremap'd address is invalid

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Date:	Fri, 11 Nov 2011 09:02:41 +0800
From:	huang ying <huang.ying.caritas@...il.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	Matt Fleming <matt@...sole-pimps.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Zhang Rui <rui.zhang@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] x86, efi: Calling __pa() with an ioremap'd address is invalid

On Tue, Nov 8, 2011 at 4:23 AM, Matthew Garrett <mjg59@...f.ucam.org> wrote:
> On Mon, Nov 07, 2011 at 03:34:48PM +0000, Matt Fleming wrote:
>
>> After the feedback from v1 I tried to unify the efi_ioremap()
>> implementations but ran into the issue detailed in the RH bug report
>> in the changelog. Unless we teach the x86 setup code that
>> EFI_RUNTIME_SERVICES_DATA regions should be part of the direct kernel
>> mapping table (even though they're marked as E820_RESERVED) I think
>> this patch makes the most sense.
>
> Honestly it seems like there may well be an argument for that. We're
> talking about executable code that the kernel will be calling - it seems
> theoretically neater for it to be added to the direct mapping. We're
> just heavily constrained by our collapsing of the EFI memory map onto
> the rather less fine-grained E820 one and the lack of any obvious way to
> extend that in an OS-specific manner. I guess we could expect the
> bootloader to conform to the standard and then re-walk the EFI memory
> map ourselves to fix things up, but eww...

Sorry for late.

Why ioremap_cache() can not work for some EFI_RUNTIME_SERVICES_DATA region?

Best Regards,
Huang Ying
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