Messages in this thread | | | Date | Mon, 07 Nov 2011 12:36:13 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH v3] x86, efi: Calling __pa() with an ioremap'd address is invalid |
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On 11/07/2011 12:23 PM, Matthew Garrett 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... >
Yes, I think it makes a lot of sense. If we need to introduce new meta-types to deal with the fact that there are EFI types that don't map to E820, then so be it... and this is *exactly* why we want the EFI setup stub to be part of the kernel image and not off in a separate bootloader, requiring a stable interface...
-hpa
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