linux-kernel - Re: EFI mixed mode + perf = rampant triple faults

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Message-ID: <CALCETrUEfQY-hnmNV9-PfDbEYLa7bVoRcsZc2X0V+mEAbfNH2g@mail.gmail.com>
Date:	Wed, 14 Jan 2015 10:38:25 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Matt Fleming <matt@...sole-pimps.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: EFI mixed mode + perf = rampant triple faults

On Wed, Jan 14, 2015 at 10:35 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Wed, Jan 14, 2015 at 10:27:47AM -0800, Andy Lutomirski wrote:
>> How are you manually triggering an MCE?  I've been playing with some
>> MCE stuff recently, but the only reasonably reliable way I know of to
>> trigger an MCE is using WHEA, and I don't have a box with WHEA, and I
>> assume your ASUS T100 doesn't either.
>
> asm volatile("int $18");

That's not a real MCE, though -- it happens synchronously instead of
at MCE priority with all the associated messiness.  Or is the idea to
just stick that in after switching to the 32-bit mode being tested?

--Andy

>
>> Tianocore makes assumptions about the kernel's GDT layout?  Yuck.
>
> Yuck indeed.
>
> --
> Regards/Gruss,
>     Boris.
>
> Sent from a fat crate under my desk. Formatting is fine.
> --



-- 
Andy Lutomirski
AMA Capital Management, LLC
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