Re: Adding kmap_atomic_prot_pfn (was: [git pull] drm patches for2.6.27-rc1)

From: Benjamin Herrenschmidt
Date: Thu Oct 23 2008 - 23:22:20 EST

On Thu, 2008-10-23 at 14:24 -0700, Linus Torvalds wrote:
> The whole point of that function has absolutely nothing to do with
> highmem, and it *must* be useful on non-highmem configurations to be
> appropriate.
> So I'd much rather create a new <linux/kmap.h> or something. Or just
> expose this from to <asm/fixmap.h> or something. Let's not confuse
> this
> with highmem, even if the implementation _historically_ was due to
> that.

Well, on powerpc, we just went (or rather, Kumar just went) through the
oops of implementing fixmap and then kmap on top of it... just because
we wanted kmap_atomic functionality on non-highmem platforms :-) (and
the fixmap approach has some other interesting features).

So yes, I agree. Typically very useful for any 32-bit processor with a
memory mapped PCI Express config space since it's something like 256M of
virtual space to map it all iirc.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at