Messages in this thread | | | Date | Fri, 1 Apr 2011 14:37:18 -0700 | Subject | Re: 2.6.38.2 breaks suspend to disk | From | Yinghai Lu <> |
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On Fri, Apr 1, 2011 at 2:30 PM, H. Peter Anvin <hpa@zytor.com> wrote: > On 04/01/2011 02:24 PM, Yinghai Lu wrote: >> On Fri, Apr 1, 2011 at 1:21 PM, H. Peter Anvin <hpa@zytor.com> wrote: >>> On 04/01/2011 12:54 PM, Yinghai Lu wrote: >>>> >>>> ok, please check if you are happy with this one. >>>> >>> >>> The best would simply be: >>> >>> mmu_cr4_features = read_cr4_safe(); >>> >>> If this has to run before we can handle exceptions, one can verify the >>> existence by testing for the CPUID instruction (a CPU has CR4 if and >>> only if it has CPUID): >>> >>> if (boot_cpu_data.cpuid_level >= 0) >>> mmu_cr4_features = read_cr4_safe(); >>> >>> ... since we set cpuid_level to -1 if there is no CPUID instruction. >> >> in that case could use read_cr4 directly. >> >> please check attached -v4 >> > > Err, yes, that's what I meant. > > Now, why the heck did you introduce a bunch of CONFIG_HIBERNATION #ifdefs?
mmu_cr4_features: have two usages: 1. for 32bit to control cr4 access in head_32.S 2. for hibernation resume.
include/asm/processor.h:extern unsigned long mmu_cr4_features; include/asm/processor.h: mmu_cr4_features |= mask; include/asm/processor.h: mmu_cr4_features &= ~mask; kernel/head_32.S:#define cr4_bits pa(mmu_cr4_features) kernel/setup.c: * mmu_cr4_features two purpose: kernel/setup.c:unsigned long mmu_cr4_features; kernel/setup.c:unsigned long mmu_cr4_features = X86_CR4_PAE; kernel/setup.c: mmu_cr4_features = read_cr4(); power/hibernate_asm_32.S: movl mmu_cr4_features, %ecx power/hibernate_asm_32.S: movl mmu_cr4_features, %ecx power/hibernate_asm_64.S: movq mmu_cr4_features(%rip), %rax power/hibernate_asm_64.S: movq mmu_cr4_features(%rip), %rax
So we don't need to read back cr4 and save it if CONFIG_HIBERNATION is not defined.
Thanks
Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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