Re: Fwd: Re: flush_cache_page()

From: Russell King
Date: Sat Jan 29 2005 - 06:42:04 EST


On Tue, Jan 11, 2005 at 04:07:09PM -0800, Linus Torvalds wrote:
> On Tue, 11 Jan 2005, Russell King wrote:
> > Any responses on this? Didn't get any last time I mailed this out.
>
> I don't have any real objections. I'd like it verified that gcc can
> compile away all the overhead on the architectures that don't use the pfn,
> since "page_to_pfn()" can be a bit expensive otherwise.. But I don't see
> anything wrong with the approach.

Thanks for the response. However, apart from Ralph, Paul and yourself,
it seems none of the other architecture maintainers care about this
patch - the original mail was BCC'd to the architecture list. Maybe
that's an implicit acceptance of this patch, I don't know.

I do know that page_to_pfn() will generate code on some platforms which
don't require it due to them declaring flush_cache_page() as a function.
However, I assert that if they don't need this overhead, that's for them
to fix up. I don't know all their quirks so it isn't something I can
tackle.

In other words, unless I actually receive some real help from the other
architecture maintainers on this to address your concerns, ARM version 6
CPUs with aliasing L1 caches (== >16K) will remain a dead dodo with
mainline Linux kernels.

(This mail BCC'd to the architecture list again in the vain hope that
someone will offer assistance.)

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/