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Subject: Re: [edk2] Corrupted EFI region
From: Andrew Fish <afish@apple.com>
In-reply-to: <20130808101730.GJ2515@console-pimps.org>
Date: Thu, 08 Aug 2013 06:46:02 -0700
Cc: edk2-devel@lists.sourceforge.net, Laszlo Ersek <lersek@redhat.com>,
        linux-efi@vger.kernel.org, Gleb Natapov <gleb@redhat.com>,
        lkml <linux-kernel@vger.kernel.org>,
        David Woodhouse <dwmw2@infradead.org>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Brian Richardson <brian.richardson@intel.com>,
        Colin Ian King <colin.king@canonical.com>
Message-id: <1AEC7AA8-D49E-485F-A634-31B4F0D07083@apple.com>
References: <51FFD5B0.9080000@redhat.com> <20130805164731.GG31845@pd.tnic>
 <52001896.1030509@redhat.com> <20130805220808.GC14067@pd.tnic>
 <20130806141036.GD14891@pd.tnic> <520116D1.2010000@redhat.com>
 <20130807151935.GJ17920@pd.tnic>
 <CCFD3CBD-62B0-4046-B96D-18CB1A815F72@apple.com>
 <20130807201908.GG2515@console-pimps.org>
 <D5982201-6DC4-469F-812A-74A8402ADEE9@apple.com>
 <20130808101730.GJ2515@console-pimps.org>
To: Matt Fleming <matt@console-pimps.org>
Sender: linux-kernel-owner@vger.kernel.org
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On Aug 8, 2013, at 3:17 AM, Matt Fleming <matt@console-pimps.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

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