Merge tag 'efi-2025-07-rc6' of https://source.denx.de/u-boot/custodians/u-boot-efi

Pull request efi-2025-07-rc6

Documentation:

* Describe usage of U-Boot environment variables in extlinux.conf

UEFI:

* Add missing variable initialization in
  efi_bootmgr_update_media_device_boot_option

doc/README.pxe

@@ -178,7 +178,8 @@ devicetree-overlay <path> [...] - if this label is chosen, use tftp to retrieve
 kaslrseed           - set this label to request random number from hwrng as kaslr seed.
 
 append <string>	    - use <string> as the kernel command line when booting this
-		      label.
+		      label. Environment variable references like ${var} are
+		      substituted before boot.
 
 initrd <path>	    - if this label is chosen, use tftp to retrieve the initrd
 		      at <path>. it will be stored at the address indicated in

doc/develop/distro.rst

@@ -92,6 +92,13 @@ That said, we have some differences to these documents, namely:
 * If ``-`` is passed as fdt argument and ``CONFIG_SUPPORT_PASSING_ATAGS`` is
   enabled, then no device tree will be used (legacy booting / pre-dtb kernel).
 
+* The ``append`` string may use environment variables. For example, an
+  A/B boot setup could use ``append root=PARTLABEL=root_${bootslot}``
+  to set the root filesystem to the right one for the selected slot,
+  assuming the ``bootslot`` environment variable is set before the
+  extlinux.conf file is processed, and the partition is labeled to
+  match.
+
 See also doc/README.pxe under 'pxe file format'.
 
 One example extlinux.conf generated by the Fedora installer is::

lib/efi_loader/efi_bootmgr.c

@@ -1133,7 +1133,7 @@ efi_status_t efi_bootmgr_update_media_device_boot_option(void)
 {
 	u32 i;
 	efi_status_t ret;
-	efi_uintn_t count, num, total;
+	efi_uintn_t count, num, total = 0;
 	efi_handle_t *handles = NULL;
 	struct eficonfig_media_boot_option *opt = NULL;