Messages in this thread | | | Date | Thu, 30 Oct 2008 14:54:56 -0700 | From | Ravikiran G Thirumalai <> | Subject | Re: [patch] x86: Fix /dev/mem mmap breakage when PAT is disabled |
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On Thu, Oct 30, 2008 at 02:29:49PM -0700, Arjan van de Ven wrote: >On Thu, 30 Oct 2008 14:21:21 -0700 >Ravikiran G Thirumalai <kiran@scalex86.org> wrote: > >> On Thu, Oct 30, 2008 at 01:21:03PM -0700, Arjan van de Ven wrote: >> >On Wed, 29 Oct 2008 19:02:03 -0700 >> >Ravikiran G Thirumalai <kiran@scalex86.org> wrote: >> > >> >well... technically the aliases are bad without PAT as well... >> > >> >> Hmm! Well, you mean if mtrr is used to change attributes? > >you can also set uncached in the pagetables, like via ioremap_uncached >and other ways. > >and /dev/mem may or may not imply cached/uncached, depending on the >open flags. > >On memory... what would that mean? >
Well, I am not denying that an incorrectly written userspace program could cause cache aliasing/crash the system I am not arguing for or against this argument at all.
However, there is what seems like an unintended change in behavior from 2.6.25 to 2.6.26 when CONFIG_STRICT_DEVMEM is disabled and PAT is disabled, which is a bug, and this patch fixes it that's all. If this was intentional, then I don't see the reason for having CONFIG_STRICT_DEVMEM!!
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