# HG changeset patch # User Wei Huang # Date 1302023857 18000 # Node ID effc147d35ce692c5d55d007a722869c372963c1 # Parent 4a9430efe643d18c8b69d377a6e70325ac7a9483 MTRR: remove k8_enable_fixed_iorrs() AMD64 defines two special bits (bit 3 and 4) RdMem and WrMem in fixed MTRR type. Their values are supposed to be 0 after BIOS hands the control to OS according to AMD BKDG. Unless OS specificially turn them on, they are kept 0 all the time. As a result, k8_enable_fixed_iorrs() is unnecessary and removed from upstream kernel (see https://patchwork.kernel.org/patch/11425/). This patch does the same thing. Signed-off-by: Wei Huang diff -r 4a9430efe643 -r effc147d35ce xen/arch/x86/cpu/mtrr/generic.c --- a/xen/arch/x86/cpu/mtrr/generic.c Tue Apr 05 12:03:35 2011 -0500 +++ b/xen/arch/x86/cpu/mtrr/generic.c Tue Apr 05 12:17:37 2011 -0500 @@ -116,20 +116,6 @@ } /** - * Enable and allow read/write of extended fixed-range MTRR bits on K8 CPUs - * see AMD publication no. 24593, chapter 3.2.1 for more information - */ -static inline void k8_enable_fixed_iorrs(void) -{ - uint64_t msr_content; - - rdmsrl(MSR_K8_SYSCFG, msr_content); - mtrr_wrmsr(MSR_K8_SYSCFG, msr_content - | K8_MTRRFIXRANGE_DRAM_ENABLE - | K8_MTRRFIXRANGE_DRAM_MODIFY); -} - -/** * Checks and updates an fixed-range MTRR if it differs from the value it * should have. If K8 extenstions are wanted, update the K8 SYSCFG MSR also. * see AMD publication no. 24593, chapter 7.8.1, page 233 for more information @@ -145,10 +131,6 @@ val = ((uint64_t)msrwords[1] << 32) | msrwords[0]; if (msr_content != val) { - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD && - boot_cpu_data.x86 == 15 && - ((msrwords[0] | msrwords[1]) & K8_MTRR_RDMEM_WRMEM_MASK)) - k8_enable_fixed_iorrs(); mtrr_wrmsr(msr, val); *changed = TRUE; }