Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"
From: Paul Gortmaker
Date: Thu Mar 10 2016 - 09:43:18 EST
[Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"] On 07/03/2016 (Mon 18:35) Toshi Kani wrote:
> On Mon, 2016-03-07 at 17:56 -0700, Toshi Kani wrote:
> And also an output of /proc/cpuinfo, please?
Here is the output of /proc/cpuinfo in the guest session, while
running on pentium dual core as host (no vmx):
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 6
model name : QEMU Virtual CPU version 2.5+
stepping : 3
cpu MHz : 2593.449
cache size : 4096 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fdiv_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 4
wp : yes
flags : fpu de pse tsc msr pae mce cx8 apic sep pge cmov mmx fxsr sse sse2 pni hypervisor
bogomips : 5186.89
clflush size : 32
cache_alignment : 32
address sizes : 36 bits physical, 32 bits virtual
> I think I know what's going on. I noticed that you have the following
> message in your dmesg files.
> [ 0.000000] MTRR: Disabled
> MTRR is set to disabled when your CPU is Intel but does not support MTRR.
> Perhaps, QEMU does not emulate MTRR?
> pat_init() is not called when MTRR is disabled. I think this dependency is
> wrong, and it needs to be fixed.
> This issue has been there for a long time, and you have been running
> essentially as PAT disabled in the past. The commit in question simply
> detected this issue.