![](https://secure.gravatar.com/avatar/5b19e9d0e834ea10ef75803718ad564b.jpg?s=120&d=mm&r=g)
At Fri, 26 Sep 2008 19:30:45 +0900, Paul Mundt wrote:
On Fri, Sep 26, 2008 at 12:04:23PM +0200, Takashi Iwai wrote:
At Thu, 25 Sep 2008 15:55:53 +0100, Pawel MOLL wrote:
One thing we can try is a patch like below. But, I'm not sure whether this is correct over all architectures, too. At best, a generic API would be helpful for such a thing...
- area->vm_page_prot = pgprot_noncached(area->vm_page_prot);
Well, it's not enough, because the kernel mapping of buffer is still cached... A hack below does the job, but it is not nice as well...
Yeah, that's not sexy, but maybe the only working case right now (better with arch-specific ifdefs).
IIRC, a similar buffer handling (via vmalloc) is used in video drivers. I suppose they don't work as well, right? DRM driver uses __vmalloc() with PAGE_KERNEL_NOCACHE, but it's only for PPC32 non-coherent.
x86 does it also, via its PAGE_AGP definition.
Right, but it doesn't seem for pages allocated via vmalloc() as in drm_scatter.c.
There are not that many platforms that define PAGE_KERNEL_NOCACHE though, so this gets a bit messy..
Indeed. We really need to have a generic API for this kind of things...
thanks,
Takashi