linux-kernel - Re: [PATCH] x86: set Pentium M as PAE capable

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Date:	Wed, 26 Feb 2014 08:45:41 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>,
	Chris Bainbridge <chris.bainbridge@...il.com>
CC:	davej@...hat.com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: set Pentium M as PAE capable

On 02/26/2014 08:44 AM, Matthew Garrett wrote:
> On Wed, Feb 26, 2014 at 07:12:59PM +0700, Chris Bainbridge wrote:
> 
>> The basic findings of the bug discussion is that people are successfully
>> running PAE kernels on Pentium M (for some unknown reason Grub skips the
>> validate_cpu code in the kernel, so existing PAE kernels will run
>> unmodified, although they do fail when booted with syslinux), and people
>> are using a user-space hack to add "pae" to /proc/cpuinfo.
> 
> grub is jumping to the 32-bit entry point and skipping the entire real 
> mode setup code. Bad grub.
> 

Yes.  Grub can be made to behave sanely by using "linux16" and
"initrd16", but of course none of the distros do it that way.

There are much worse problems with that.

	-hpa

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