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Subject: Re: [REGRESSION][v4.9.y][v4.10.y] x86/efi: Only map RAM into EFI page
 tables if in mixed-mode
To: Laura Abbott <labbott@redhat.com>, matt@codeblueprint.co.uk
References: <31c63945-fa81-de18-941b-9021f3d9f16c@canonical.com>
 <d5f1ba6b-06ed-b5b0-1b0e-58d5f385f7c2@redhat.com>
Cc: waiman.long@hpe.com, ard.biesheuvel@linaro.org,
        Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>, tytso@mit.edu,
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From: Joseph Salisbury <joseph.salisbury@canonical.com>
Message-ID: <4ff32ae9-ccb9-6ad9-8ea7-2f1fc17468d1@canonical.com>
Date: Thu, 2 Feb 2017 15:49:45 -0500
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On 02/02/2017 03:36 PM, Laura Abbott wrote:
> On 02/02/2017 12:17 PM, Joseph Salisbury wrote:
>> Hi Matt,
>>
>> A kernel bug report was opened against Ubuntu [0].  After a kernel
>> bisect, it was found that reverting the following commit resolved this bug:
>>
>> commit 1297667083d5442aafe3e337b9413bf02b114edb
>> Author: Matt Fleming <matt@codeblueprint.co.uk>
>> Date:   Mon Sep 19 13:09:09 2016 +0100
>>
>>     x86/efi: Only map RAM into EFI page tables if in mixed-mode
>>
>>
>> The regression was introduced as of v4.8-rc8.  It also still affects
>> current mainline.
>>
>> I was hoping to get your feedback, since you are the patch author.  Do
>> you think gathering any additional data will help diagnose this issue,
>> or would it be best to submit a revert request?
>>
>>
>> Thanks,
>>
>> Joe
>>
>> [0] http://pad.lv/1659340
>>
>>
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> You might try https://marc.info/?l=linux-kernel&m=148553171703761
> which fixed https://bugzilla.redhat.com/show_bug.cgi?id=1384238
>
> Thanks,
> Laura

Thanks for the suggestion, Laura.  Ard also pointed to the same patch. 
I'll have it tested and report back.


Thanks again,


Joe