From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Date: Wed, 09 Feb 2005 20:03:31 +0000 Subject: RE: [PATCH] CPU hotplug returns CPUs to SAL Message-Id: <1107979412.5478.69.camel@tdi> List-Id: References: <1107970828.5478.22.camel@tdi> In-Reply-To: <1107970828.5478.22.camel@tdi> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Wed, 2005-02-09 at 11:51 -0800, Luck, Tony wrote: > > But the BSP doesn't need to save anything. We'll always have N-1 SAL > >states saved and N-1 CPUs that can be taken offline. As long as we > >don't hard link a state to a specific CPU, we're in good shape. I've > >been testing on my boxes with an order that intentionally gives CPUs the > >state saved off of another CPU on OS entry. I appear to be able to make > >the BSP return to SAL as well, but I don't think the rest of the hotplug > >code is ready for this (the other CPU doesn't seem to be getting > >scheduled). > > That sounds worrying ... it assumes that the SAL thinks that > cpus are fungible, which might not be true on ccNUMA systems. Ok, I suppose it could be interpreted that Table 3-2 defining cr.lid as unchanged locks a state to a specific CPU... too bad. Alex -- Alex Williamson HP Linux & Open Source Lab