From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: kexec and kdump on Xen?? Date: Thu, 17 Apr 2014 10:50:19 +0100 Message-ID: <534FA3DB.3070103@citrix.com> References: <20140414081126.GA1632@router-fw-old.local.net-space.pl> <20140414132632.GA6173@router-fw-old.local.net-space.pl> <20140416111005.GA6251@router-fw-old.local.net-space.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Zhang, Yang Z" Cc: "david.vrabel@citrix.com" , Daniel Kiper , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 17/04/14 02:19, Zhang, Yang Z wrote: > >>> Here is my environment: >>> Xen version: latest Xen >>> Xen boot command: >>> kernel (hd0,0)/boot/xen.gz dom0_mem=4096M loglvl=all >>> guest_loglvl=all >> conring_size=4M crashkernel=128M@64M >>> module (hd0,0)/boot/vmlinuz-xen o >> root=UUID=03a5e7c4-b8d0-45b4-a090-c34b06821cea pci=noaer max_loop=64 >> 3 debug >>> module (hd0,0)/boot/initrd-xen.img kexec version with Xen enabled: >>> kexec-tools 2.0.6 released 18 April 2014 >>> >>> Also, it shows error when trying to kexec (Xen -> Xen) ./kexec -l >>> /boot/xen.gz Segmentation fault (core dumped) >> We were focusing more on kdump than on other scenarios. >> I suppose that kexec-tools assume that this compressed ELF file is >> Linux Kernel and tries load it as usual which of course is completely >> wrong. You should load Xen with at least "-t multiboot-x86" argument (read help printed by kexec). >> However, I am not sure that this loader is actively maintained and works. >> >> Daniel > Thanks for your comments. > > After investigation, I found some bugs (One is the segment overlap check failure and another one is related to x2apic). With some workarounds, now I am able to kexec from Xen into Linux. > But it still fails to run kdump(Xen->linux). I add some debug messages in the key code path. It shows kexec_reloc() will cause machine reboot. Is it a known issue? > > BTW: Have you ever tried kdump(Xen->linux) successfully? If yes, can you share some BKMs? Thanks. > > Best regards, > Yang You are going to have to be more descriptive than this with setups and problems. As for real examples, XenServer unconditionally sets up a native crash kernel and does use it in the case of a Xen/dom0 crash. It does work reliably and repeatedly[1] and is routinely tested. ~Andrew [1] We are aware of one hardware specific bug whereby the crash kernel fails to set up a timer interrupt. Investigating it is on my todo list.