Re: [Qemu-devel] [RFC][PATCH 09/15] introduce a new monitor command 'dump' to dump guest's memory

[Eric Blake <eblake@redhat.com>]

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On 01/18/2012 08:07 PM, Wen Congyang wrote:
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  Makefile.target  |    8 +-
>  dump.c           |  590 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  dump.h           |    3 +
>  hmp-commands.hx  |   16 ++
>  hmp.c            |    9 +
>  hmp.h            |    1 +
>  monitor.c        |    3 +
>  qapi-schema.json |   13 ++
>  qmp-commands.hx  |   26 +++
>  9 files changed, 665 insertions(+), 4 deletions(-)
>  create mode 100644 dump.c
> 

> +void qmp_dump(const char *file, Error **errp)
> +{
> +    const char *p;
> +    int fd = -1;
> +    DumpState *s;
> +
> +#if !defined(WIN32)
> +    if (strstart(file, "fd:", &p)) {
> +        fd = qemu_get_fd(p);
> +        if (fd == -1) {
> +            error_set(errp, QERR_FD_NOT_FOUND, p);
> +            return;
> +        }
> +    }
> +#endif

Thanks for implementing fd support off the bat.

> +
> +    if  (strstart(file, "file:", &p)) {
> +        fd = open(p, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY);

Use of O_CREAT requires that you pass a third argument to open()
specifying the mode_t to use.

> +++ b/hmp-commands.hx
> @@ -828,6 +828,22 @@ new parameters (if specified) once the vm migration finished successfully.
>  ETEXI
>  
>      {
> +        .name       = "dump",
> +        .args_type  = "file:s",
> +        .params     = "file",
> +        .help       = "dump to file",
> +        .user_print = monitor_user_noop,
> +        .mhandler.cmd = hmp_dump,
> +    },

What if I want to dump only a fraction of the memory?  I think you need
optional start and length parameters, to limit how much memory to be
dumped, rather than forcing me to dump all memory at once.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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