Re: [patch -mm series] ia64 specific /dev/mem handlers

From: Andrew Morton <akpm_at_osdl.org>
Date: 2005-02-22 21:03:09
jes@trained-monkey.org (Jes Sorensen) wrote:
>
> Hi,
> 
> This patch introduces ia64 specific read/write handlers for /dev/mem
> access which is needed to avoid uncached pages to be accessed through
> the cached kernel window which can lead to random corruption. It also
> introduces a new page-flag PG_uncached which will be used to mark the
> uncached pages. I assume this may be useful to other architectures as
> well where the CPU may use speculative reads which conflict with
> uncached access. In addition I moved do_write_mem to be under
> ARCH_HAS_DEV_MEM as it's only ever used if that is defined.
> 
> The patch is needed for the new ia64 special memory driver (mspec -
> former fetchop).
> 
> Patch is relative to 2.6.11-rc3-mm2 and relies on the ARCH_HAS_DEV_MEM
> flag which isn't in Linus' nor Tony's trees yet.

Is it possible to avoid consuming a page flag?

If this is an ia64-only (or 64-bit-only) thing I guess we could use bit 32.

> +		if (page->flags & PG_uncached)

dude.  That ain't gonna work ;)
-
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Received on Tue Feb 22 05:09:00 2005

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:36 EST