Document config_distro_bootcmd environment variables for interactive booting.
config_distro_bootcmd.h defines a common boot environment for multiple platforms, including several environment variables that are intended for interactive use by an end-user. Document which variables are considered public interfaces that must remain compatible in future u-boot versions. Signed-off-by: Karsten Merker <merker@debian.org> Acked-by: Stephen Warren <swarren@nvidia.com>
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/*
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/*
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* (C) Copyright 2014 Red Hat Inc.
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* (C) Copyright 2014 Red Hat Inc.
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* Copyright (c) 2014-2015, NVIDIA CORPORATION. All rights reserved.
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* Copyright (c) 2014-2015, NVIDIA CORPORATION. All rights reserved.
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* Copyright (C) 2015 K. Merker <merker@debian.org>
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*
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*
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* SPDX-License-Identifier: GPL-2.0+
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* SPDX-License-Identifier: GPL-2.0+
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*/
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*/
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@ -339,3 +340,49 @@ scan_dev_for_scripts:
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If you want to disable boot.scr on all disks, set the value to something
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If you want to disable boot.scr on all disks, set the value to something
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innocuous, e.g. setenv scan_dev_for_scripts true.
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innocuous, e.g. setenv scan_dev_for_scripts true.
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Interactively booting from a specific device at the u-boot prompt
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=================================================================
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For interactively booting from a user-selected device at the u-boot command
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prompt, the environment provides predefined bootcmd_<target> variables for
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every target defined in boot_targets, which can be run be the user.
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If the target is a storage device, the format of the target is always
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<device type><device number>, e.g. mmc0. Specifying the device number is
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mandatory for storage devices, even if only support for a single instance
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of the storage device is actually implemented.
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For network targets (dhcp, pxe), only the device type gets specified;
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they do not have a device number.
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Examples:
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- run bootcmd_usb0
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boots from the first USB mass storage device
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- run bootcmd_mmc1
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boots from the second MMC device
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- run bootcmd_pxe
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boots by tftp using a pxelinux.cfg
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The list of possible targets consists of:
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- network targets
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* dhcp
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* pxe
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- storage targets (to which a device number must be appended)
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* mmc
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* sata
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* scsi
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* ide
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* usb
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Other *boot* variables than the ones defined above are only for internal use
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of the boot environment and are not guaranteed to exist or work in the same
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way in future u-boot versions. In particular the <device type>_boot
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variables (e.g. mmc_boot, usb_boot) are a strictly internal implementation
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detail and must not be used as a public interface.
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