On 04/02/2018 10:52 AM, Linus Torvalds wrote: > On Mon, Apr 2, 2018 at 10:27 AM, Dave Hansen > <dave.hansen@xxxxxxxxxxxxxxx> wrote: >> >> Aside: _PAGE_GLOBAL is ignored when CR4.PGE=1, so why do we >> even go to the trouble of filtering it anywhere? > > I'm assuming this is a typo, and you mean "when CR4.PGE=0". Yes, that is a typo. > The question you raise may be valid, but within the particular context > of *this* patch it is not. I thought it was relevant because I was asking myself: Why is it OK for the (old) code to be doing this: > - if (pgprot_val(req_prot) & _PAGE_PRESENT) > - pgprot_val(req_prot) |= _PAGE_PSE | _PAGE_GLOBAL; When _PAGE_GLOBAL is not supported. This "Aside" got moved a bit away from the comment, but I actually mean to refer to the comment that talks about canon_pgprot(): >> canon_pgprot() will clear it if unsupported, >> but we *always* set it. and its use of __supported_pte_mask. I'll redo the changelog a bit and hopefully capture all this along with correcting the typo.
