linux-kernel - Re: Fail to early boot with v2.6.27-rc2 to at least v2.6.29-rc2 due to dc1e35c

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Date:	Mon, 19 Jan 2009 13:57:36 -0800
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Avuton Olrich <avuton@...il.com>
Cc:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: Fail to early boot with v2.6.27-rc2 to at least v2.6.29-rc2 due to dc1e35c

On Mon, Jan 19, 2009 at 01:46:37PM -0800, Avuton Olrich wrote:
> On Mon, Jan 19, 2009 at 12:11 PM, Suresh Siddha
> <suresh.b.siddha@...el.com> wrote:
> > Avuton, Does your bios has an option which says limit the cpuid
> > vector limit to '2' or something. Can you disable that option and
> > re-check? It will typically be located under cpu configuration settings.
> 
> You're the winner of the prize. The culprit in my bios was:
>
> Max CPUID Value Limit: Enabled

Though the bios is the culprit and this option will severely limit
the cpu capabilities that OS can take advantage of, OS should fallback
to a safer mode. I will have a patch for it.

Also, I wonder, if we should complain/scream during boot if we find only
fewer cpuid levels on modern generation cpu's.

thanks,
suresh
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