Please add CC list to Kumagai-san, makedumpfile maintainer, and Dave Anderson in order to let them know this development.
(2013/05/07 16:16), Qiao Nuohan wrote: > Hi, all > > Command 'dump-guest-memory' was introduced to dump guest's memory. But the > vmcore's format is only elf32 or elf64. The message is here: > http://lists.gnu.org/archive/html/qemu-devel/2012-04/msg03379.html > > These patches are used to make 'dump-guest-memory' be able to dump guest's > memory in kdump-compressed format. Then vmcore can be much smaller, and > easily be delivered. > It should be stressed here that compression feature is *regression*. > Note, similar to 'dump-guest-memory': > 1. The guest should be x86 or x86_64. The other arch is not supported now. > 2. 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. > 3. The cpu's state is stored in QEMU note. > 4. The vmcore are able to be compressed with zlib, lzo or snappy. zlib is > available by default, and option '--enable-lzo' or '--enable-snappy' > should be used with configure to make lzo or snappy available. > > the kdump-compressed format is: Rather than detail of format, qemu people should want to know more general information about kdump-compressed format. They should think "What this format?" now. At least the following is needed: the kdump-compressed format is *linux specific* *linux standard* crash dump format used in kdump framework. > File offset > +------------------------------------------+ 0x0 > | main header (struct disk_dump_header) | > |------------------------------------------+ block 1 > | sub header (struct kdump_sub_header) | > |------------------------------------------+ block 2 > | 1st-dump_bitmap | > |------------------------------------------+ block 2 + X blocks > | 2nd-dump_bitmap | (aligned by block) > |------------------------------------------+ block 2 + 2 * X blocks > | page desc for pfn 0 (struct page_desc) | (aligned by block) > | page desc for pfn 1 (struct page_desc) | > | : | > | page desc for pfn Z (struct page_desc) | > |------------------------------------------| (not aligned by block) > | page data (pfn 0) | > | page data (pfn 1) | > | : | > | page data (pfn Z) | > +------------------------------------------+ offset_eraseinfo > | : | > +------------------------------------------+ Layout itself is important information. Not only describing this here, it's better to put it anywhere of source code or point at IMPLEMENTATION file in makedumpfile which describes orignal spec. -- Thanks. HATAYAMA, Daisuke
