From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35195) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c4Tz7-0006Ua-CG for qemu-devel@nongnu.org; Wed, 09 Nov 2016 09:36:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c4Tz3-00032r-Bt for qemu-devel@nongnu.org; Wed, 09 Nov 2016 09:36:17 -0500 Received: from mx3-phx2.redhat.com ([209.132.183.24]:54674) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c4Tz3-00032V-3t for qemu-devel@nongnu.org; Wed, 09 Nov 2016 09:36:13 -0500 Date: Wed, 9 Nov 2016 09:36:08 -0500 (EST) From: Dave Anderson Message-ID: <1365301332.14030682.1478702168917.JavaMail.zimbra@redhat.com> In-Reply-To: <20161109050248.GA4431@dhcp-128-65.nay.redhat.com> References: <20161109030146.GA3802@dhcp-128-65.nay.redhat.com> <20161109031729.GA3675@dhcp-128-65.nay.redhat.com> <962ee966-641a-2f74-3e26-7c7967fa8f7e@cn.fujitsu.com> <20161109050248.GA4431@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] virsh dump (qemu guest memory dump?): KASLR enabled linux guest support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dave Young Cc: Wen Congyang , lersek@redhat.com, qemu-devel@nongnu.org, bhe@redhat.com ----- Original Message ----- > On 11/09/16 at 11:58am, Wen Congyang wrote: > > On 11/09/2016 11:17 AM, Dave Young wrote: > > > Drop qiaonuohan, seems the mail address is wrong.. > > > > > > On 11/09/16 at 11:01am, Dave Young wrote: > > >> Hi, > > >> > > >> Latest linux kernel enabled kaslr to randomiz phys/virt memory > > >> addresses, we had some effort to support kexec/kdump so that crash > > >> utility can still works in case crashed kernel has kaslr enabled. > > >> > > >> But according to Dave Anderson virsh dump does not work, quoted messages > > >> from Dave below: > > >> > > >> """ > > >> with virsh dump, there's no way of even knowing that KASLR > > >> has randomized the kernel __START_KERNEL_map region, because there is no > > >> virtual address information -- e.g., like "SYMBOL(_stext)" in the kdump > > >> vmcoreinfo data to compare against the vmlinux file symbol value. > > >> Unless virsh dump can export some basic virtual memory data, which > > >> they say it can't, I don't see how KASLR can ever be supported. > > >> """ > > >> > > >> I assume virsh dump is using qemu guest memory dump facility so it > > >> should be first addressed in qemu. Thus post this query to qemu devel > > >> list. If this is not correct please let me know. > > > > IIRC, 'virsh dump --memory-only' uses dump-guest-memory, and 'virsh dump' > > uses migration to dump. > > Do they need different fixes? Dave, I guess you mean --memory-only, but > could you clarify and confirm it? As I understand it, the "--memory-only" option uses a new "dump-guest-memory" QEMU monitor command that creates an ELF kdump vmcore clone. Dave > > > > > I think I should study kaslr first... > > Thanks for taking care of it. > > > > > Thanks > > Wen Congyang > > > > >> > > >> Could you qemu dump people make it work? Or we can not support virt dump > > >> as long as KASLR being enabled. Latest Fedora kernel has enabled it in > > >> x86_64. > > >> > > >> Thanks > > >> Dave > > > > > > > > > > > > > > > >