Re: [PATCH 3/4] x86, head_32: Remove second CPUID detection fromdefault_entry

From: H. Peter Anvin
Date: Mon Feb 11 2013 - 12:22:52 EST

On 02/11/2013 09:15 AM, Borislav Petkov wrote:
On Mon, Feb 11, 2013 at 07:49:14AM -0800, H. Peter Anvin wrote:
What about CPUs with inconsistent cpuid levels? Yes, they can and do
happen, as we discussed on IRC.

Yes, this should still work. We're doing the EFLAGS.ID dance right at
the beginning of default_entry on each cpu and cache cpuld level in
new_cpu_data for the time we're in this code.

What this particular patch removes is the yet-another EFLAGS.ID dance
which we IMHO unnecessarily did after enabling paging.

So basically nothing changes wrt handling inconsistent cpuid levels and
MSR mis-programming - we still should be taking care of those cases.

Cool. I misread your 0/4 cover and hadn't quite dug into the details yet.


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at