Re: [Xen-devel] [PATCH 3 of 6 V2] libxl: QMP stop/resume & refactor QEMU suspend/resume/save

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 1 Feb 2012, rshriram@xxxxxxxxx wrote:
> # HG changeset patch
> # User Shriram Rajagopalan <rshriram@xxxxxxxxx>
> # Date 1328070813 28800
> # Node ID 3ca830009da79443bb445d983a34f5f78664cdf4
> # Parent  9f0a67bd54db89a23078913db578df72c5dba2e3
> libxl: QMP stop/resume & refactor QEMU suspend/resume/save
> 
> Implement QMP stop and resume functionality and split
> device model save into 3 parts:
>  suspend_dm(domid)
>  save_dm(domid, fd)
>  resume_dm(domid)
> 
> Integrate Device model suspend into suspend_common_callback
>
> Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
> 
> diff -r 9f0a67bd54db -r 3ca830009da7 tools/libxl/libxl_dom.c
> --- a/tools/libxl/libxl_dom.c Tue Jan 31 20:33:33 2012 -0800
> +++ b/tools/libxl/libxl_dom.c Tue Jan 31 20:33:33 2012 -0800
> @@ -425,6 +425,61 @@ static int libxl__domain_suspend_common_
>      return rc ? 0 : 1;
>  }
>  
> +int libxl__domain_suspend_device_model(libxl__gc *gc, uint32_t domid)
> +{
> +    libxl_ctx *ctx = libxl__gc_owner(gc);
> +    int ret = 0, fd2 = -1;
> +    const char *filename = libxl__device_model_savefile(gc, domid);
> +
> +    switch (libxl__device_model_version_running(gc, domid)) {
> +    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL: {
> +        LIBXL__LOG(ctx, LIBXL__LOG_DEBUG,
> +                   "Saving device model state to %s", filename);
> +        libxl__qemu_traditional_cmd(gc, domid, "save");
> +        libxl__wait_for_device_model(gc, domid, "paused", NULL, NULL, NULL);
> +        break;
> +    }
> +    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
> +        if (libxl__qmp_stop(gc, domid))
> +            return ERROR_FAIL;
> +        fd2 = open(filename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | 
> S_IWUSR);
> +        if (fd2 < 0) {
> +            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
> +                             "Unable to create a QEMU save file\n");
> +            return ERROR_FAIL;
> +        }
> +        /* Save DM state into fd2 */
> +        ret = libxl__qmp_migrate(gc, domid, fd2);
> +        if (ret)
> +            unlink(filename);
> +        close(fd2);
> +        fd2 = -1;
> +        break;
> +    default:
> +        return ERROR_INVAL;
> +    }
> +

Why do you need to introduce libxl__qmp_stop and libxl__qmp_resume?

Also keep in mind that I am about to change the command sent to save the
state of devices to "save_devices" because "migrate" is not working
properly with Xen.

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