Re: [Regression] "x86-64/efi: Use EFI to deal with platform wallclock" prevents my machine from booting

From: Yinghai Lu
Date: Fri Aug 10 2012 - 15:22:08 EST


On Thu, Aug 9, 2012 at 1:51 AM, Matt Fleming <matt.fleming@xxxxxxxxx> wrote:
> On Tue, 2012-08-07 at 11:50 +0100, Jan Beulich wrote:
>> >
>> > I managed to find a machine to reproduce this on and it looks like the
>> > ASUS firmware engineers are upto their old tricks of referencing
>> > physical addresses after we've taken control of the memory map,
>>
>> Yippie. On such systems we simply can't do any runtime calls.
>> Should we add a command line option forcing efi_native to false,
>> thus suppressing all runtime calls? Or would the "noefi" one be
>> enough already?
>
> I think a better solution for this, seeing as there appear to be *so*
> many ASUS machines in the wild with this inability to do virtual EFI
> calls, is to provide a 1:1 mapping as well as our regular virt->phys
> mapping for the benefit of the firmware. We can load our special page
> table in efi_call_*, etc.
>
> One thing to note is that because of breakage seen on Apple machines
> last time Matthew tried this approach, we (the kernel) can't actually
> access the 1:1 mapping, it would exist purely for the benefit of
> firmware that was broken enough to reference physical addresses after
> SetVirtualAddressMap().
>

What is solution for this regression?

It seems Jan's commit broke our setup with UEFI too.

Assume other systems with AMI code base would have same problem.

Thanks

Yinghai
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