From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Date: Wed, 09 Feb 2005 18:19:43 +0000 Subject: Re: [PATCH] CPU hotplug returns CPUs to SAL Message-Id: <1107973183.5478.31.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 Hi Ashok, Sorry I missed your patch. Your assembly is certainly cleaner than mine. We seem to have several differences in the state that actually gets saved and restored though. For instance, I see you're saving k0, which is listed as scratch in the spec, but none of the fp, predicate, branch registers, region registers, or preserved general registers. Shouldn't a few more of those be preserved under "standard calling conventions"? Also, what do you think about treating the saved state as a stack? This could eventually allow the BSP to be sent off spinning in SAL. Thanks, Alex On Wed, 2005-02-09 at 09:53 -0800, Ashok Raj wrote: > On Wed, Feb 09, 2005 at 09:40:28AM -0800, Alex Williamson wrote: > > Hi Alex > > In fact i did submit a patch for this about a month ago. I was sharing some > code from mca side for tlb purge, and this code has been in the swamp for > several weeks now. I hope they are settled now, and i will re submit my > patches once again. > > link from old post > > http://marc.theaimsgroup.com/?l=linux-ia64&m0239954713260&w=2 > > I will repost to match whats there in tony-'s test/release tree asap. > > ashok > > > > When a CPU is sent offline, it currently goes into a dummy spin > > loop > > and pretends to be gone. This patch returns the CPU back to SAL via > > the > > mechanism described in the SAL spec. The state of secondary CPUs is > > saved off to a dynamically allocated stack for use on return to SAL. > > I've munged the _start code in head.S to avoid trampling over some of > > the preserved registers before we get a chance to save them. The > > assembly could probably use some optimizations, but these are hardly > > performance paths. It seems to work reliably on zx1 and sx1000 boxes, > > but needs some exposure on others. Patch against current bk. Thanks, > > > > Alex -- Alex Williamson HP Linux & Open Source Lab