xen: write information about supported backends

Add a Xenstore directory for each supported pv backend. This will allow
Xen tools to decide which backend type to use in case there are
multiple possibilities.

The information is added under
/local/domain/<backend-domid>/device-model/<domid>/backends
before the "running" state is written to Xenstore. Using a directory
for each backend enables us to add parameters for specific backends
in the future.

This interface is documented in the Xen source repository in the file
docs/misc/qemu-backends.txt

In order to reuse the Xenstore directory creation already present in
hw/xen/xen_devconfig.c move the related functions to
hw/xen/xen_backend.c where they fit better.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Message-id: 1463062421-613-3-git-send-email-jgross@suse.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
index b4b4ff0af2..63364f71d0 100644
--- a/include/hw/xen/xen_backend.h
+++ b/include/hw/xen/xen_backend.h
@@ -28,6 +28,7 @@ struct XenDevOps {
     int       (*free)(struct XenDevice *xendev);
     void      (*backend_changed)(struct XenDevice *xendev, const char *node);
     void      (*frontend_changed)(struct XenDevice *xendev, const char *node);
+    int       (*backend_register)(void);
 };
 
 struct XenDevice {
@@ -63,6 +64,7 @@ extern const char *xen_protocol;
 extern DeviceState *xen_sysdev;
 
 /* xenstore helper functions */
+int xenstore_mkdir(char *path, int p);
 int xenstore_write_str(const char *base, const char *node, const char *val);
 int xenstore_write_int(const char *base, const char *node, int ival);
 int xenstore_write_int64(const char *base, const char *node, int64_t ival);