Re: [edk2] Corrupted EFI region

Andrew Fish
2013-08-08T13:46:02Z

On Aug 8, 2013, at 3:17 AM, Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org> wrote:

> On Wed, 07 Aug, at 02:10:28PM, Andrew Fish wrote:
>> Well the issue I see is I don't think OS X or Windows are doing this.
>> So I'm guessing there is some unique thing beings done on the Linux
>> side and we don't have good tests to catch bugs in the EFI
>> implementations. If the Linux loader hides the bugs and we don't hit
>> them with other operating systems they are never going to get fixed.
>> It would be good if we could track down some of these issues and make
>> a request for some tests that can help catch these issues. The tests
>> would be part of UEFI.org, but since some of us play in both worlds we
>> can forward the known issues to the UEFI test work group.
>
> I'm all for helping to develop tests that catch these kind of bugs.
> What's the next step?
>

I'll bring this up with UEFI.org.

>> Is it possible to have a switch to turn off the not required behavior
>> (hiding EFI implementation bugs) so that bad platforms could be
>> detected? This would be a good thing to try on platforms at the
>> upcoming UEFI Plugfest hosted by the Linux Foundation and the UEFI
>> Forum, so the bad behavior can be detected and the vendors can fix the
>> issue.
>
> We don't tend to provide switches for the kernel to turn off workarounds
> because users run the risk of inadvertently stopping their machines from
> booting correctly. Also, because the major distributions will always
> enable the workarounds, the kernel would need to be built manually to
> see any kind of informative error message.
>
> What we do have though is the Firmware Testsuite - fwts,
>
> https://wiki.ubuntu.com/Kernel/Reference/fwts
>
> I know that Brian (Cc'd) has been doing some excellent advocacy work,
> getting people at plugfetsts to run this testsuite which tests for
> implementation bugs from within a Linux environment.
>
>> PS Also maybe it would be possible to key this work around behavior on
>> the EFI/UEFI version. So for example no work-around after UEFI v2.3.1?
>
> That would really depend on who has seen this bug and on which
> platforms. Is there a particular reason that mapping the boot services
> regions as-is would cause problems?
>

1) The firmware bug could also be a security hole and thus needs to get fixed.
2) The kernel gets locked into a design that does not follow the specification, and this limits future design options.
3) Makes the code more complex to maintain and test.

> --
> Matt Fleming, Intel Open Source Technology Center