From mboxrd@z Thu Jan  1 00:00:00 1970
From: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
Subject: Re: [Xen-devel] lguest: unhandled trap 13 and
	CONFIG_MICROCODE_INTEL_EARLY
Date: Wed, 08 May 2013 20:24:50 -0700
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To: Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
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On 05/08/2013 06:43 PM, Rusty Russell wrote:
> 
> OK, that confirms my understanding it's lguest-only.
> 
> To return to the immediate proposal: I'd like to expand it KEEP_SEGMENTS
> to say "don't do any privileged ops before the platform entry point"
> which is what it used to do (before we added those config options), and
> still does (if they're disabled).
> 
> This fixes lguest for those configs, and if there *are* any other users,
> this just means they don't support OLPC machines (since 2.6.37) or early
> microcode (3.9).  OLPC + KEEP_SEGMENTS is vanishingly unlikely (the OLPC
> bootloader doesn't use it), and early microcode never worked with
> paravirt anyway (those native_cpuid() calls).
> 
> Failing that, second best to remove KEEP_SEGMENTS, and have lguest
> 'emulate' (ie. skip!) those instructions.  We already do this for in/out
> instructions, see drivers/lguest/x86/core.c emulate_insn().  More code,
> but it's lguest code.
>

Or we can skip the microcode stuff for platform == 2.

	-hpa