From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Wed, 26 Jul 2006 15:33:35 +0000 Subject: RE: [Patch] Don't alloc empty frame in ia64_switch_mode_phys Message-Id: <000001c6b0c8$e0f3a710$6154e984@amr.corp.intel.com> List-Id: References: <1153870600.3286.72.camel@linux-znh> In-Reply-To: <1153870600.3286.72.camel@linux-znh> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Zou Nan hai wrote on Tuesday, July 25, 2006 4:37 PM > I think ia64_switch_mode_phys and ia64_switch_mode_virt > does not need to alloc an empty frame. > An empty frame is required by loadrs but flushrs > does not need that. This patch would make your previous "Do not assume output registers be reservered" unnecessary, isn't it? It will automatically solve the problem you are trying to fix in previous patch. The real issue to me is that ia64_switch_mode_phys() creates a zero stack frame before turning off interrupt. If the zero frame alloc instruction is removed, the current register stack frame ought to be safe because they should be preserved by the interrupt return path. - Ken