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

From: H. Peter Anvin
Date: Wed Feb 26 2014 - 11:46:13 EST


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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