From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp02.citrix.com ([66.165.176.63]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aMYZW-0001un-Qg for kexec@lists.infradead.org; Fri, 22 Jan 2016 10:04:04 +0000 Subject: Re: [Xen-devel] [PATCH] xen: Add support for dom0 with Linux kernel 3.19 and newer References: <1453407231-25432-1-git-send-email-daniel.kiper@oracle.com> From: David Vrabel Message-ID: <56A1FE76.40201@citrix.com> Date: Fri, 22 Jan 2016 10:03:34 +0000 MIME-Version: 1.0 In-Reply-To: <1453407231-25432-1-git-send-email-daniel.kiper@oracle.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Daniel Kiper , crash-utility@redhat.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Cc: jgross@suse.com, olaf@aepfle.de, keir@xen.org, dmair@suse.com, andrew.cooper3@citrix.com, ptesarik@suse.cz, dslutz@verizon.com, anderson@redhat.com, david.vrabel@citrix.com, jbeulich@suse.com, boris.ostrovsky@oracle.com On 21/01/16 20:13, Daniel Kiper wrote: > Linux kernel commit 054954eb051f35e74b75a566a96fe756015352c8 > (xen: switch to linear virtual mapped sparse p2m list), which > appeared in 3.19, introduced linear virtual mapped sparse p2m > list. If readmem() reads p2m then it access this list using > physical addresses. Sadly, VMA to physical address translation > in crash requires access to p2m list. This means that we have > a chicken and egg problem. In general this issue must be solved > by introducing some changes in libxl, Linux kernel and crash > (I have added this task to my long TODO list). However, in dom0 > case we can use crash_xen_info_t.dom0_pfn_to_mfn_frame_list_list > which is available out of the box. So, let's use it and make > at least some users happy. I'm confused. How does a virtual address to (pseudo-)physical address lookup require access to the p2m? Surely this is a walk of the page tables followed by a M2P lookup on the MFN in the L1 PTE? David _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec