[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [patch] nx bit shouldn't get set when disabled
Keir Fraser wrote: > On 8 Jun 2005, at 20:47, Scott Parish wrote: > >>> Why does x86_64 get pte_mfn, but not pae i386? I think pci-dma.c >>> should probably be shared between i386 and x86/64. >> >> Last time i checked, the linux side of i386 pae wasn't merged into >> bk, so i have nothing to test such a patch against. I'll plan on >> getting a pae setup going again and sending a patch to gerd. > > The functions that are changed aren't pae-specific, and they are > already in the xen/i386 tree. They can be patched in anticipation of > pae, even though they can only be properly tested non-pae for the time > being. I'm not inclined to take patches for xen/x86_64/pci-dma.c > anyway: I think we can patch the xen/i386 one and share it with > xen/x86_64. Otherwise we're going to get unnecessary divergence > between what really ought to be two identical files. (I already did > this for arch/xen/i386/kernel/time.c, for example.) > >>> Why the extra mask ops with __supported_pte_mask? Native x86/64 >>> builds obviously don't need them... >> >> Definitions such as __PAGE_KERNEL set NX, but as Jun pointed out, >> those should only be set when NX mode is enabled. > > So the extra masking isn't required? > > -- Keir Hold on. Scott, in your patch: - pfn = pte->pte >> PAGE_SHIFT; + mfn = pte_mfn(*pte); +#define pte_mfn(_pte) (((_pte).pte & PTE_MASK) >> PAGE_SHIFT) These should not be necessary if pte is created correctly (w/ or w/o NX bit depending on __supported_pte_mask) in the first place, as Keir pointed out. That's what I meant by "We should fix the creator of the pte (by __supported_pte_mask), not the consumer of it." And you always cut off the NX bit in your patch. So remove the changes to pci-dma.c and init.c. If that does not work, move check_efer to right before pda_init(0) in x86_64_start_kernel() in head64.c. Jun --- Intel Open Source Technology Center _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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