From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Wed, 18 Feb 2004 18:59:03 +0000 Subject: Re: PXM/Nid/SLIT patch Message-Id: <16435.46583.57234.573875@napali.hpl.hp.com> List-Id: References: <40321CF7.5020301@hp.com> In-Reply-To: <40321CF7.5020301@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Wed, 18 Feb 2004 17:08:58 +0000, Christoph Hellwig said: Christoph> On Wed, Feb 18, 2004 at 10:33:29AM -0500, Robert Picco wrote: >> This PXM value (255) isn't a SLIT or PXM defined quantity. It is really >> specific to HP cell machines. For example, a machine configured with >> two cells will report three PXMs. Two for the CPUs and one for the >> interleaved memory at magic PXM 255. The firmware doesn't report SLIT >> information for PXM 255. The patch approximates the SLIT value for PXM >> 255. I have attempted to arrive at code which doesn't break non-HP >> hardware configurations. I have assumed the way the initialization code >> was written that all NIDs require memory. Otherwise >> reserve_pernode_space will fail. Christoph> I know HP basically owns the IA64 ports This comment concerns me. I certainly have always tried to judge patches based on their technical merits for Linux. Is there anything in particular that I did (or didn't) do that you found objectionable? If so, please let me know. Christoph> but honestly can't you fix the firmware to return sane Christoph> information instead? i.e. move the above fix to firmware Christoph> instead of letting linux fixup the reported data. Hmmh, I'm no NUMA-expert and it isn't clear to me whether the patch is working around a firmware-bug or a limitation in the Linux NUMA code. I don't see off-hand why it should be illegal to have a memory config with only one node with memory. The whole PXM_MAGIC business looks strange to me though. Can someone explain? --david