Re: [Qemu-devel] [PATCH 1/1] qmp: extend QMP to provide read/write access to physical memory

[Eric Blake <eblake@redhat.com>]

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On 11/26/2014 01:41 AM, Bryan D. Payne wrote:
> This patch adds a new QMP command that sets up a domain socket. This
> socket can then be used for fast read/write access to the guest's
> physical memory. The key benefit to this system over existing solutions
> is speed. Using this patch, guest memory can be copied out at a rate of
> ~200MB/sec, depending on the hardware. Existing solutions only achieve
> a small fraction of this speed.
> 
> Signed-off-by: Bryan D. Payne <bdpayne@acm.org>
> ---
>  Makefile.target |   2 +-
>  memory-access.c | 200 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  memory-access.h |  11 ++++
>  monitor.c       |  10 +++
>  qmp-commands.hx |  27 ++++++++

Where is the *.json file that adds the QMP command contract?

> +++ b/qmp-commands.hx
> @@ -609,6 +609,33 @@ Example:
>  EQMP
>  
>      {
> +        .name       = "pmemaccess",
> +        .args_type  = "path:s",
> +        .params     = "path",
> +        .help       = "mount guest physical memory image at 'path'",
> +        .user_print = monitor_user_noop,
> +        .mhandler.cmd_new = do_physical_memory_access,
> +    },
> +
> +SQMP
> +pmemaccess
> +----------
> +
> +Mount guest physical memory image at 'path'.
> +
> +Arguments:
> +
> +- "path": mount point path (json-string)
> +
> +Example:
> +
> +-> { "execute": "pmemaccess",
> +             "arguments": { "path": "/tmp/guestname" } }

Sounds like you are missing this entry (probably best to put it in the
top-level qapi-schema.json):

{ 'command': 'pmemaccess', 'data': { 'path': 'str' } }

as well as documentation that mentions it is targetted for addition in 2.3.

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


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