> +void __cpuinit pat_init(void)
> +{
> + /* Set PWT+PCD to Write-Combining. All other bits stay the same */
> + if (cpu_has_pat) {
All the old CPUs (PPro etc.) with known PAT bugs need to clear this flag
now in their CPU init functions. It is fine to be aggressive there
because these old systems have lived so long without PAT they can do
so forever. So perhaps it's best to just white list it only for newer
CPUs on the Intel side at least.
Another problem is that there are some popular modules (ATI, Nvidia for once)
who reprogram the PAT registers on their own, likely different. Need some way to detect
that case I guess, otherwise lots of users will see strange malfunctions.
Maybe recheck after module load?
> + |||
> + 000 WB default
> + 010 UC_MINUS _PAGE_PCD
> + 011 WC _PAGE_WC
> + PAT bit unused */
> + pat = PAT(0,WB) | PAT(1,WT) | PAT(2,UC_MINUS) | PAT(3,WC) |
> + PAT(4,WB) | PAT(5,WT) | PAT(6,UC_MINUS) | PAT(7,WC);
> + rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
> + wrmsrl(MSR_IA32_CR_PAT, pat);
> + __flush_tlb_all();
> + asm volatile("wbinvd");
Have you double checked this is the full procedure from the manual? iirc there
were some steps missing.
-Andi
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