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Add documentation for the script bootmeth. Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de> Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
52 lines
1.9 KiB
ReStructuredText
52 lines
1.9 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+:
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Script Bootmeth
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===============
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This bootmeth provides a way to locate and run a script on a block or network
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device. It can also support SPI flash.
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For a block device the file is read from the selected partition, which must use
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a supported filesystem. The subdirectory to search in is defined by the bootstd
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list of prefixes (``{"/", "/boot"}`` by default) and can be adjust with the
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`filename-prefixes` property in the bootstd device.
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For a network device, the filename is obtained from the `boot_script_dhcp`
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environment variable and the file is read using tftp. It must be in the
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top-level directory of the tftp server.
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In either case (file or network), the bootmeth searches for the file and creates
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a bootflow if found. The bootmeth searches for "boot.scr.uimg" first, then
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"boot.scr" if not found.
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For SPI flash, a script is read from flash using the offset provided by the
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"script_offset_f" environment variable.
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Some attempt is made to identify the Operating System: so far this only detects
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an `Armbian <https://www.armbian.com>`_
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distro. For block devices, if a file called "boot.bmp" exists in the same
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directory then it is used as the bootflow logo.
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When the bootflow is booted, the bootmeth sets these environment variables:
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devtype
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device type (e.g. "usb", "mmc", "ethernet" or "spi_flash")
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devnum
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device number, corresponding to the device 'sequence' number
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``dev_seq(dev)``
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distro_bootpart
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(block devices only) partition number on the device (numbered from 1)
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prefix
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prefix used to find the file
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mmc_bootdev
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device number (same as `devnum`), set for sunxi mmc devices only
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The script file must be a FIT or a legacy uImage. It is loaded into memory and
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executed.
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The compatible string "u-boot,script" is used for the driver. It is present
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if `CONFIG_BOOTMETH_SCRIPT` is enabled.
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