From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brendan Cully Subject: [PATCH 0 of 5] Make checkpointing backwards compatible with older kernels Date: Fri, 12 Jan 2007 15:03:07 -0700 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org This set of patches makes checkpointing backwards compatible with older kernels. Checkpointable kernels now create a xenstore entry called "control/feature-resumable" which xc save -c checks before attempting to checkpoint a domain. It also writes a new SIF_RESUMABLE flag into the suspend record, which xc_linux_restore uses to decide whether it is safe to set the hypercall return value. Although pre-checkpoint linux images ignore the return value, I've heard that solaris bails out if the result is anything but 0. Another possibly simpler strategy would be to flip the return values, so 1 means the call is resuming in the source domain and 0 means it is in a new domain and must reconnect. This is what older kernels (that are only ever restored in a new domain) expect anyway.