From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Horman Date: Thu, 15 Nov 2007 17:28:26 +0000 Subject: Re: [PATCH] XPC heartbeat timer function must run on CPU 0 Message-Id: <20071115172805.GA7095@verge.net.au> List-Id: References: <20071107135306.99AAF11C415@aqua.americas.sgi.com> In-Reply-To: <20071107135306.99AAF11C415@aqua.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 Wed, Nov 14, 2007 at 02:19:15PM -0800, Luck, Tony wrote: > >> Wouldn't that cpu appear to the new OS instance as cpu0? If so, then > >> it should not be an issue. > > > > No, I don't believe that it does. > > I can try and test this theory if it helps. > > Perhaps my mind is corrupted by x86 thoughts. > > We are talking about logical cpu0 here. Surely the new instance > must call whatever cpu it is running on first "0". E.g. I could > have used kexec to switch to a UP kernel that only supports cpu0. I took a look into this, and yes you are right. Regardless of which physical CPU is used to boot on, it is always logical cpu 0. So the problem that I was thinking about doesn't exist. Silly me. I also noticed that even if it was posisble for logical cpu 0 to not be present, the patch will still work as the hearbeat code would just end up being run on the prevailing logical cpu. So no problem x2 :-) -- Horms, California Edition