Re: [Xen-devel] [PATCH v4 --for 4.6 COLOPre 15/25] tools/libxl: check QEMU state before resume dm

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jul 15, 2015 at 01:54:12PM +0100, Ian Campbell wrote:
> On Wed, 2015-07-15 at 13:48 +0100, Ian Campbell wrote:
> > >      switch (libxl__device_model_version_running(gc, domid)) {
> > >      case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL: {
> > > -        libxl__qemu_traditional_cmd(gc, domid, "continue");
> > > -        libxl__wait_for_device_model_deprecated(gc, domid, "running", 
> > > NULL, NULL, NULL);
> > > +        uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
> > > +
> > > +        path = libxl__device_model_xs_path(gc, dm_domid, domid, 
> > > "/state");
> > > +        state = libxl__xs_read(gc, XBT_NULL, path);
> > > +        if (state != NULL && !strcmp(state, "paused")) {
> > > +            libxl__qemu_traditional_cmd(gc, domid, "continue");
> > 
> > Please can you explain the apparent discrepancy between the use of
> > dm_domid and domid here?
> 
> I see from the next patch that this pattern came from the existing
> libxl_domain_unpause, which hopes to use this helper in the future.
> 
> Looking at git annotate:
> 83cc69fa        (Ian Jackson    2012-06-28 18:43:28 +0100       1045)    if 
> (type == LIBXL_DOMAIN_TYPE_HVM) {
> 1fc3aeb3        (   Wei Liu     2015-04-09 19:49:25 +0100       1046)        
> uint32_t dm_domid = libxl_get_stubdom_id(ctx, domid);
> 1fc3aeb3        (   Wei Liu     2015-04-09 19:49:25 +0100       1047)
> 1fc3aeb3        (   Wei Liu     2015-04-09 19:49:25 +0100       1048)        
> path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
> bdf07e8e        (Ian Jackson    2011-12-12 17:48:42 +0000       1049)        
> state = libxl__xs_read(gc, XBT_NULL, path);
> d1c7c3ef        (Keir Fraser    2009-11-30 10:53:39 +0000       1050)        
> if (state != NULL && !strcmp(state, "paused")) {
> 0cb90b31        (Shriram Rajagopalan    2012-02-09 18:07:48 +0000       1051) 
>            libxl__qemu_traditional_cmd(gc, domid, "continue");
> 47cb2273        (Ian Jackson    2013-10-14 17:26:01 +0100       1052)         
>    libxl__wait_for_device_model_deprecated(gc, domid, "running",
> 3b6eaa3e        (Ian Campbell   2011-05-24 15:57:24 +0100       1053)         
>                                 NULL, NULL, NULL);
> d1c7c3ef        (Keir Fraser    2009-11-30 10:53:39 +0000       1054)        }
> 
> It seems this came from Wei in 1fc3aeb3aa26 "libxl: use new QEMU
> xenstore protocol". I suspect it was a mistake. Wei?
> 

No, it's not.

libxl__qemu_traditional_cmd accepts domid and then it calls
libxl_get_stubdom_id to extract dm_domid.

Wei.

> Ian.

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