libxl: domain_config_setdefault: Document use of domid

We are going to want to call this from a site which has a domid which
is good for logging but not the domid of the domain we are creating
(namely, the stub device domain).

Consequently, add the same comment to
libxl__arch_passthrough_mode_setdefault.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>

tools/libxl/libxl_arch.h

@@ -74,7 +74,7 @@ void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
 
 _hidden
 int libxl__arch_passthrough_mode_setdefault(libxl__gc *gc,
-                                            uint32_t domid,
+                                     uint32_t domid /* for logging, only */,
                                             libxl_domain_config *d_config,
                                             const libxl_physinfo *physinfo);
 

tools/libxl/libxl_create.c

@@ -891,7 +891,7 @@ static unsigned long libxl__get_required_iommu_memory(unsigned long maxmem_kb)
 
 int libxl__domain_config_setdefault(libxl__gc *gc,
                                     libxl_domain_config *d_config,
-                                    uint32_t domid)
+                                    uint32_t domid /* for logging, only */)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     int ret;