[image] Generalise concept of selected image

Most image flags are independent values: any combination of flags may
be set for any image, and the flags for one image are independent of
the flags for any other image.  The "selected" flag does not follow
this pattern: at most one image may be marked as selected at any time.

When invoking a kernel via the UEFI shim, there will be multiple
"special" images: the selected kernel itself, the shim image, and
potentially a shim-signed GRUB binary to be used as a crutch to assist
shim in loading the kernel (since current versions of the UEFI shim
are not capable of directly loading a Linux kernel).

Remove the "selected" image flag and replace it with a general concept
of an image tag with the same semantics: a given tag may be assigned
to at most one image, an image may be found by its tag only while the
image is currently registered, and a tag will survive unregistration
and reregistration of an image (if it has not already been assigned to
a new image).  For visual consistency, also replace the current image
pointer with a current image tag.

The image pointer stored within the image tag holds only a weak
reference to the image, since the selection of an image should not
prevent that image from being freed.  (The strong reference to the
currently executing image is held locally within the execution scope
of image_exec(), and is logically separate from the current image
pointer.)

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/usr/imgmgmt.c b/src/usr/imgmgmt.c
index 94f3d2ce0..92bf236f9 100644
--- a/src/usr/imgmgmt.c
+++ b/src/usr/imgmgmt.c
@@ -156,13 +156,17 @@ int imgacquire ( const char *name_uri, unsigned long timeout,
  * @v image		Executable/loadable image
  */
 void imgstat ( struct image *image ) {
+	struct image_tag *tag;
+
 	printf ( "%s : %zd bytes", image->name, image->len );
 	if ( image->type )
 		printf ( " [%s]", image->type->name );
+	for_each_table_entry ( tag, IMAGE_TAGS ) {
+		if ( tag->image == image )
+			printf ( " [%s]", tag->name );
+	}
 	if ( image->flags & IMAGE_TRUSTED )
 		printf ( " [TRUSTED]" );
-	if ( image->flags & IMAGE_SELECTED )
-		printf ( " [SELECTED]" );
 	if ( image->flags & IMAGE_AUTO_UNREGISTER )
 		printf ( " [AUTOFREE]" );
 	if ( image->flags & IMAGE_HIDDEN )