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

[Matt Fleming <matt@console-pimps.org>]

On Fri, 2011-11-11 at 09:02 +0800, huang ying wrote:
> On Tue, Nov 8, 2011 at 4:23 AM, Matthew Garrett <mjg59@srcf.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?

It looks like ioremap_cache() maps the region with the NX bit set.

-- 
Matt Fleming, Intel Open Source Technology Center