summaryrefslogtreecommitdiff
path: root/doc/develop
diff options
context:
space:
mode:
authorTom Rini <[email protected]>2025-06-28 08:10:43 -0600
committerTom Rini <[email protected]>2025-06-28 08:10:43 -0600
commit7027b445cc0bfb86204ecb1f1fe596f5895048d9 (patch)
treef27d6f3425dea4bc984c6fede0e7ce73f5d17917 /doc/develop
parent359e3012921f2fc2d43f3c4e320a752173f82b82 (diff)
parente80baf06af50a4c8c6f41e9b67f9931f964ced87 (diff)
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
Diffstat (limited to 'doc/develop')
-rw-r--r--doc/develop/distro.rst7
1 files changed, 7 insertions, 0 deletions
diff --git a/doc/develop/distro.rst b/doc/develop/distro.rst
index 1d2f9c4c32b..01efce40a29 100644
--- a/doc/develop/distro.rst
+++ b/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::