On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote:this is a configuration option telling about the way
+static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size)If be_alloc is a flag (which I am not sure about) --- should it be set
+{
+ struct xen_drm_front_drm_info *drm_info = dev->dev_private;
+ struct xen_gem_object *xen_obj;
+ int ret;
+
+ size = round_up(size, PAGE_SIZE);
+ xen_obj = gem_create_obj(dev, size);
+ if (IS_ERR_OR_NULL(xen_obj))
+ return xen_obj;
+
+ if (drm_info->cfg->be_alloc) {
+ /*
+ * backend will allocate space for this buffer, so
+ * only allocate array of pointers to pages
+ */
+ xen_obj->be_alloc = true;
to true *after* you've successfully allocated your things?
in this use-case we map pages provided by the backend
+ ret = gem_alloc_pages_array(xen_obj, size);Why are you allocating balloon pages?
+ if (ret < 0) {
+ gem_free_pages_array(xen_obj);
+ goto fail;
+ }
+
+ ret = alloc_xenballooned_pages(xen_obj->num_pages,
+ xen_obj->pages);
-boris
+ if (ret < 0) {
+ DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n",
+ xen_obj->num_pages, ret);
+ goto fail;
+ }
+
+ return xen_obj;
+ }
+ /*
+ * need to allocate backing pages now, so we can share those
+ * with the backend
+ */
+ xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE);
+ xen_obj->pages = drm_gem_get_pages(&xen_obj->base);
+ if (IS_ERR_OR_NULL(xen_obj->pages)) {
+ ret = PTR_ERR(xen_obj->pages);
+ xen_obj->pages = NULL;
+ goto fail;
+ }
+
+ return xen_obj;
+
+fail:
+ DRM_ERROR("Failed to allocate buffer with size %zu\n", size);
+ return ERR_PTR(ret);
+}
+