Re: [patch 4/5] mm: add vm_insert_pfn helpler

[Nick Piggin]

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 ;)


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