Re: [REGRESSION][x86] Commit f5b2831d65 cause boot failure in VMware ESXi 5.1 guest

From: Qu Wenruo
Date: Sun Dec 28 2014 - 20:18:51 EST

-------- Original Message --------
Subject: Re: [REGRESSION][x86] Commit f5b2831d65 cause boot failure in VMware ESXi 5.1 guest
From: Juergen Gross <jgross@xxxxxxxx>
To: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
Date: 2014å12æ27æ 21:51
On 12/26/2014 02:57 AM, Qu Wenruo wrote:
Hi all,

When testing v3.19-rc1 kernel(in fact, try to test), the kernel itself
fail to boot on VMware ESXi 5.1 guest.
The boot failure is quite easy to describe, only one line is output:
"Probing EDD (edd=off to disable)...ok"

No other output(including warning/bug_on/backtrace or whatever) and the
guest just hangs.
It's OK on v3.18, so it's a regression.

Bisect points to the following commit:
commit f5b2831d654167d77da8afbef4d2584897b12d0c
Author: Juergen Gross <jgross@xxxxxxxx>
Date: Mon Nov 3 14:02:02 2014 +0100

x86: Respect PAT bit when copying pte values between large and
normal pages

The PAT bit in the ptes is not moved to the correct position when
copying page protection attributes between entries of different sized
pages. Translate the ptes according to their page size.

I have also created the kernel BZ report:

Hopes this can be resolved in next rc.

As the same issue has been reported with VMWare workstation which was
related to an error in the PAT MSR emulation of VMWare, I guess this
will be the same problem. I've already sent a patch.

You should be able to boot with the "nopat" kernel option.

Thanks for the explanation. Again the closed source blob to blame.

Anyway, the nopat option works.

Great thanks
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