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Re: [Qemu-devel] [PATCH 0/9] Make monitor command 'dump-guest-memory' du
From: |
HATAYAMA Daisuke |
Subject: |
Re: [Qemu-devel] [PATCH 0/9] Make monitor command 'dump-guest-memory' dump in kdump-compressed format |
Date: |
Wed, 08 May 2013 18:03:54 +0900 |
User-agent: |
Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 |
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
- Re: [Qemu-devel] [PATCH 9/9] Make monitor command 'dump-guest-memory' dump in kdump-compressed format, (continued)
- [Qemu-devel] [PATCH 7/9] Add API to free buf used by creating header, bitmap and page, Qiao Nuohan, 2013/05/07
- [Qemu-devel] [PATCH 3/9] Move include and struct definition to dump.h, Qiao Nuohan, 2013/05/07
- [Qemu-devel] [PATCH 2/9] Add API to manipulate cache_data, Qiao Nuohan, 2013/05/07
- [Qemu-devel] [PATCH 1/9] Add API to manipulate dump_bitmap, Qiao Nuohan, 2013/05/07
- [Qemu-devel] [PATCH 5/9] Add API to create data of dump bitmap, Qiao Nuohan, 2013/05/07
- Re: [Qemu-devel] [PATCH 0/9] Make monitor command 'dump-guest-memory' dump in kdump-compressed format,
HATAYAMA Daisuke <=