From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Thu, 09 Sep 2004 17:21:56 +0000 Subject: Re: [RFC 0/4] Add SN2 Special Memory driver. Message-Id: <20040909182156.A12644@infradead.org> List-Id: References: <20040909163638.GA23178@lnx-holt.americas.sgi.com> In-Reply-To: <20040909163638.GA23178@lnx-holt.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Thu, Sep 09, 2004 at 11:36:38AM -0500, Robin Holt wrote: > > This driver provides three different devices for mmap'ing pages which > are not visible to the kernel. > > sgi_fetchops) atomic operations performed by the SN2 memory controller. > These operations are performed using uncached memory > references with an offset of the address specifying the > operation (add, sub) to perform. > > sgi_uncached) Provides a device which supports mapping pages which > will only be referenced uncached. These use the Intel ia64 > write combining feature. These need to be in a separate > granule from regular memory to prevent the FSB from having > both a cached and an uncached reference to a memory location. > > sgi_cached) Provides a device which support cached operations from the > processor and uncached from processors outside the coherence > domain. This provides rapid read access to the 16 words in the > cache line to data that was written uncached by remote processors. >From your description only the first two actually use special SGI hardware features, or did I misread the descruption? If so they should probably have a separate driver that works on all ia64 hardware.