[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 bugs : bogomips : 5186.89 clflush size : 32 cache_alignment : 32 address sizes : 36 bits physical, 32 bits virtual power management: Paul. -- > > 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. > > Thanks, > -Toshi
