Messages in this thread | | | Date | Wed, 11 Oct 2006 23:30:22 +0200 | From | Thomas Hellström <> | Subject | Re: [patch 4/5] mm: add vm_insert_pfn helpler |
| |
Nick Piggin wrote:
>On Wed, Oct 11, 2006 at 12:12:19PM +0200, Thomas Hellstrom wrote: > > >>Nick, I just realized: would it be possible to have a pgprot_t argument >>to this one, instead of it using vma->vm_pgprot? >> >>The motivation for this (DRM again) is that some architectures (powerpc) >>cannot map the AGP aperture through IO space, but needs to remap the >>page from memory with a nocache attribute set. Others need special >>pgprot settings for write-combined mappings. >> >>Now, there's a possibility to change vma->vm_pgprot during the first >>->fault(), but again, we only have the mmap_sem in read mode. >> >> > >I don't see a problem with that. It would be nice if vm_pgprot could >be kept in synch with the pte protections, but I guess a crazy >driver should be allowed to do anything it wants ;) > > > > :). Actually, the caching bits are sort of left out from the mm code anyway. For example, mprotect will reset them, which is sort of a security risc, since an unpriviliged user can call mprotect on uncached page mappings, causing inconsistent mappings and stability problems.
Thomas
- 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/
| |