From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH RFCv3 0/8] toolstack-based approach to pvhvm guest kexec Date: Tue, 7 Oct 2014 14:28:45 +0100 Message-ID: <5433EA8D.6080500@citrix.com> References: <1412687413-22818-1-git-send-email-vkuznets@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XbUos-0007p0-Gg for xen-devel@lists.xenproject.org; Tue, 07 Oct 2014 13:28:50 +0000 In-Reply-To: <1412687413-22818-1-git-send-email-vkuznets@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Vitaly Kuznetsov , xen-devel@lists.xenproject.org Cc: Andrew Cooper , Andrew Jones , Ian Campbell , Jan Beulich List-Id: xen-devel@lists.xenproject.org On 07/10/14 14:10, Vitaly Kuznetsov wrote: > Changes from RFC/WIPv2: > > Here is a slightly different approach to memory reassignment. Instead of > introducing new (and very doubtful) XENMEM_transfer operation introduce > simple XEN_DOMCTL_set_recipient operation and do everything in free_domheap_pages() > handler utilizing normal domain destroy path. This is better because: > - The approach is general-enough > - All memory pages are usually being freed when the domain is destroyed > - No special grants handling required > - Better supportability I like this idea, but this really isn't my area of expertise so you'll have to wait to see what Jan and Tim say. > With regards to PV: > Though XEN_DOMCTL_set_recipient works for both PV and HVM this patchset does not > bring PV kexec/kdump support. xc_domain_soft_reset() is limited to work with HVM > domains only. The main reason for that is: it is (in theory) possible to save p2m > and rebuild them with the new domain but that would only allow us to resume execution > from where we stopped. If we want to execute new kernel we need to build the same > kernel/initrd/bootstrap_pagetables/... structure we build to boot PV domain initially. > That however would destroy the original domain's memory thus making kdump impossible. > To make everything work additional support from kexec userspace/linux kernel is > required and I'm not sure it makes sense to implement all this stuff in the light of > PVH. I'm fine with limiting this to HVM guests. David