Hello Wen, From: Wen Congyang <we...@cn.fujitsu.com> Subject: [Qemu-devel] [RFC][PATCT 0/5 v2] dump memory when host pci device is used by guest Date: Fri, 09 Dec 2011 15:57:26 +0800
> Hi, all > > 'virsh dump' can not work when host pci device is used by guest. We have > discussed this issue here: > http://lists.nongnu.org/archive/html/qemu-devel/2011-10/msg00736.html > > We have determined to introduce a new command dump to dump memory. The core > file's format can be elf. > > Note: > 1. The guest should be x86 or x86_64. The other arch is not supported. > 2. If you use old gdb, gdb may crash. I use gdb-7.3.1, and it does not crash. > 3. If the OS is in the second kernel, gdb may not work well, and crash can > work by specifying '--machdep phys_addr=xxx' in the command line. The > reason is that the second kernel will update the page table, and we can > not get the page table for the first kernel. I guess still the current implementation breaks vmalloc'ed area that needs page tables originally located in the first 640kB, right? If you want to do so in a correct way, you need to identify a position of backup region and get data of 1st kernel's page tables. But it needs debugging information of guest kernel, and I don't think it good idea that qemu uses too guest-specific information. On the other hand, I have a basic question. Can this command used for creating live dump? or crash dump only? Thanks. HATAYAMA, Daisuke