Re: Missing cache flush.

David Woodhouse (dwmw2@infradead.org)
Tue, 05 Jun 2001 10:05:35 +0100


davem@redhat.com said:
> One way to do this, (even portably :-) is via displacement flushes.
> Linus mentioned this.

> Basically if you know the L2 cache size and the assosciativity you can
> do this as long as you can get a "2 * L2 cache size * assosciativity"
> piece of contiguous physical memory. When you need this "simon says"
> flush, you basically read this physical memory span and this will
> guarentee that all dirty data has exited the L2 cache.

Fine. So it should be possible to do it on all architectures with
physically-indexed caches - that's good. Architectures with
virtually-indexed caches are going to have explicit cache management
functionality anyway, presumably :)

Obviously the algorithm you describe should not be implemented in
arch-independent drivers. It should be in include/asm-*, for those
architectures which _can't_ do it with a single cache management instruction
(or loop of same).

What shall we call this function? The intuitive "flush_dcache_range" appears
to have already been taken.

--
dwmw2

- 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/