Re: [Qemu-devel] [PATCH v5 0/9] Make 'dump-guest-memory' dump in kdump-compressed format

[Qiao Nuohan]

Hi, all

Would you please give some advice about how to continue my series?

My patches have stuck for several months, because I was not allowed to add an
option before introspection is implemented. After observing mails about
introspection, I find it is still not confirmed its implement way. Since I got
a deadline about this feature(in three months), I have to ask for some advice
about these patches.

First, I hope to confirm whether it is impossible to add an option to 'dump-
guest-memory'. If the answer is impossible, then should I still wait for
introspection or just change to add a new command?


On 07/09/2013 03:30 PM, Qiao Nuohan wrote:
> Hi, all
>
> The last version is here:
> http://lists.gnu.org/archive/html/qemu-devel/2013-05/msg03866.html
>
> 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
>
> Compared with migration, the missing of compression feature means regression
> to 'dump-guest-memory'. So we post these patches to make 'dump-guest-memory' be
> able to dump guest's in kdump-compressed format. Then vmcore can be much
> smaller, and easily to be delivered.
>
> The kdump-compressed format is *linux specific* *linux standard* crash dump
> format used in kdump framework. The kdump-compressed format is readable only
> with the crash utility, and it can be smaller than the ELF format because of
> the compression support. To get more detailed information about
> kdump-compressed format, please refer to the following URL:
> http://sourceforge.net/projects/makedumpfile/
>
> 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 specified with 'configure' to make lzo or snappy available.
>
> Changelog:
> Changes from v4 to v5:
> 1. using flatten format to avoid using temporary files according to Stefan's
>     comments
> 2. Address Andreas's comments about coding style
>
> Changes from v3 to v4:
> 1. change to avoid conflict with Andreas's patches
> 2. rebase
>
> Changes from v2 to v3:
> 1. Address Eric's comment
>
> Changes from v1 to v2:
> 1. Address Eric&  Daniel's comment: fix manner of string copy.
> 2. Address Eric's comment: replace reinventing new constants by using the
>     ready-made ones accoring.
> 3. Address Andreas's comment: remove useless include.
>
> Qiao Nuohan (9):
>    dump: Add argument to write_elfxx_notes
>    dump: Add API to write header of flatten format
>    dump: Add API to write vmcore
>    dump: Add API to write elf notes to buffer
>    dump: add API to write dump header
>    dump: Add API to write dump_bitmap
>    dump: Add APIs to operate DataCache
>    dump: Add API to write dump pages
>    dump: Make kdump-compressed format available for 'dump-guest-memory'
>
>   configure             |   50 +++
>   dump.c                |  873 ++++++++++++++++++++++++++++++++++++++++++++++++-
>   hmp-commands.hx       |   12 +-
>   hmp.c                 |   23 ++-
>   include/sysemu/dump.h |  127 +++++++
>   qapi-schema.json      |   22 ++-
>   qmp-commands.hx       |    6 +-
>   7 files changed, 1088 insertions(+), 25 deletions(-)


--
Regards
Qiao Nuohan