Hi!
> EFER varies like %cr4 depending on the cpu capabilities, and which cpu
> capabilities we want to make use of. So save/restore it make certain
> we have the same EFER value when we are done.
I still think that comment is right: EFER is function(cpu
capabilities, kernel version, kernel cmdline); and that _should_ be
constant accross suspend.
Anyway saving it does not hurt and code is probably easier to
understand.
ACK.
Pavel
> /* XMM0..XMM15 should be handled by kernel_fpu_begin(). */
> - /* EFER should be constant for kernel version, no need to handle it. */
> /*
> * segment registers
> */
> @@ -50,6 +49,7 @@ void __save_processor_state(struct saved
> /*
> * control registers
> */
> + rdmsrl(MSR_EFER, ctxt->efer);
> asm volatile ("movq %%cr0, %0" : "=r" (ctxt->cr0));
> asm volatile ("movq %%cr2, %0" : "=r" (ctxt->cr2));
> asm volatile ("movq %%cr3, %0" : "=r" (ctxt->cr3));
> @@ -75,6 +75,7 @@ void __restore_processor_state(struct sa
> /*
> * control registers
> */
> + wrmsrl(MSR_EFER, ctxt->efer);
> asm volatile ("movq %0, %%cr8" :: "r" (ctxt->cr8));
> asm volatile ("movq %0, %%cr4" :: "r" (ctxt->cr4));
> asm volatile ("movq %0, %%cr3" :: "r" (ctxt->cr3));
> --- linux-2.6.19-rc6-reloc/include/asm-x86_64/suspend.h~x86_64-Add-EFER-to-the-set-registers-saved-by-save_processor_state 2006-11-17 00:08:16.000000000 -0500
> @@ -17,6 +17,7 @@ struct saved_context {
> u16 ds, es, fs, gs, ss;
> unsigned long gs_base, gs_kernel_base, fs_base;
> unsigned long cr0, cr2, cr3, cr4, cr8;
> + unsigned long efer;
> u16 gdt_pad;
> u16 gdt_limit;
> unsigned long gdt_base;
> _
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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