Add documentation for the script bootmeth.
Signed-off-by: Simon Glass sjg@chromium.org Reviewed-by: Quentin Schulz quentin.schulz@cherry.de ---
Changes in v2: - Adjustments from Heinrich's comments
doc/develop/bootstd/index.rst | 1 + doc/develop/bootstd/overview.rst | 2 +- doc/develop/bootstd/script.rst | 52 ++++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+), 1 deletion(-) create mode 100644 doc/develop/bootstd/script.rst
diff --git a/doc/develop/bootstd/index.rst b/doc/develop/bootstd/index.rst index 2c5d2d3fade..9d35b567d55 100644 --- a/doc/develop/bootstd/index.rst +++ b/doc/develop/bootstd/index.rst @@ -11,4 +11,5 @@ Standard Boot pxelinux qfw cros + script sandbox diff --git a/doc/develop/bootstd/overview.rst b/doc/develop/bootstd/overview.rst index add054f3088..e4924b55ae7 100644 --- a/doc/develop/bootstd/overview.rst +++ b/doc/develop/bootstd/overview.rst @@ -414,7 +414,7 @@ Bootmeth drivers are provided for booting from various media:
- :doc:`extlinux / syslinux <extlinux>` boot from a storage device - :doc:`extlinux / syslinux <extlinux>` boot from a network (PXE) - - U-Boot scripts from disk, network or SPI flash + - :doc:`U-Boot scripts <script>` from disk, network or SPI flash - EFI boot using bootefi from disk - VBE - :doc:`ChromiumOS <cros>` ChromiumOS boot from a disk diff --git a/doc/develop/bootstd/script.rst b/doc/develop/bootstd/script.rst new file mode 100644 index 00000000000..58ddc1cae1d --- /dev/null +++ b/doc/develop/bootstd/script.rst @@ -0,0 +1,52 @@ +.. SPDX-License-Identifier: GPL-2.0+: + +Script Bootmeth +=============== + +This bootmeth provides a way to locate and run a script on a block or network +device. It can also support SPI flash. + +For a block device the file is read from the selected partition, which must use +a supported filesystem. The subdirectory to search in is defined by the bootstd +list of prefixes ({"/", "/boot"} by default) and can be adjust with the +`filename-prefixes` property in the bootstd device. + +For a network device, the filename is obtained from the `boot_script_dhcp` +environment variable and the file is read using tftp. It must be in the +top-level directory of the tftp server. + +In either case (file or network), the bootmeth searches for the file and creates +a bootflow if found. The bootmeth searches for "boot.scr.uimg" first, then +"boot.scr" if not found. + +For SPI flash, a script is read from flash using the offset provided by the +"script_offset_f" environment variable. + +Some attempt is made to identify the Operating System: so far this only detects +an `Armbian https://www.armbian.com`_ +distro. For block devices, if a file called "boot.bmp" exists in the same +directory then it is used as the bootflow logo. + +When the bootflow is booted, the bootmeth sets these environment variables: + + devtype + device type (e.g. "usb", "mmc", "ethernet" or "spi_flash") + + devnum + device number, corresponding to the device 'sequence' number + `dev_seq(dev)` + + distro_bootpart + (block devices only) partition number on the device (numbered from 1) + + prefix + prefix used to find the file + + mmc_bootdev + device number (same as `devnum`), set for sunxi mmc devices only + +The script file must be a FIT or a legacy uImage. It is loaded into memory and +executed. + +The compatible string "u-boot,script" is used for the driver. It is present +if `CONFIG_BOOTMETH_SCRIPT` is enabled.