u-boot/include/bootm.h
Simon Glass 51bb33846a bootm: Support string substitution in bootargs
In some cases it is necessary to pass parameters to Linux so that it will
boot correctly. For example, the rootdev parameter is often used to
specify the root device. However the root device may change depending on
whence U-Boot loads the kernel. At present it is necessary to build up
the command line by adding device strings to it one by one.

It is often more convenient to provide a template for bootargs, with
U-Boot doing the substitution from other environment variables.

Add a way to substitute strings in the bootargs variable. This allows
things like "rootdev=${rootdev}" to be used in bootargs, with the
${rootdev} substitution providing the UUID of the root device.

For example, to substitute the GUID of the kernel partition:

  setenv bootargs "console=/dev/ttyS0 rootdev=${uuid}/PARTNROFF=1
		kern_guid=${uuid}"
  part uuid mmc 2:2 uuid
  bootm

This is particularly useful when the command line from another place. For
example, Chrome OS stores the command line next to the kernel itself. It
depends on the kernel version being used as well as the hardware features,
so it is extremely difficult to devise a U-Boot script that works on all
boards and kernel versions. With this feature, the command line can be
read from disk and used directly, with a few substitutions set up.

Signed-off-by: Simon Glass <sjg@chromium.org>
2020-12-04 19:48:29 -05:00

128 lines
3.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* (C) Copyright 2000-2009
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*/
#ifndef _BOOTM_H
#define _BOOTM_H
#include <image.h>
struct cmd_tbl;
#define BOOTM_ERR_RESET (-1)
#define BOOTM_ERR_OVERLAP (-2)
#define BOOTM_ERR_UNIMPLEMENTED (-3)
/*
* Continue booting an OS image; caller already has:
* - copied image header to global variable `header'
* - checked header magic number, checksums (both header & image),
* - verified image architecture (PPC) and type (KERNEL or MULTI),
* - loaded (first part of) image to header load address,
* - disabled interrupts.
*
* @flag: Flags indicating what to do (BOOTM_STATE_...)
* @argc: Number of arguments. Note that the arguments are shifted down
* so that 0 is the first argument not processed by U-Boot, and
* argc is adjusted accordingly. This avoids confusion as to how
* many arguments are available for the OS.
* @images: Pointers to os/initrd/fdt
* @return 1 on error. On success the OS boots so this function does
* not return.
*/
typedef int boot_os_fn(int flag, int argc, char *const argv[],
bootm_headers_t *images);
extern boot_os_fn do_bootm_linux;
extern boot_os_fn do_bootm_vxworks;
int do_bootelf(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]);
void lynxkdi_boot(image_header_t *hdr);
boot_os_fn *bootm_os_get_boot_func(int os);
#if defined(CONFIG_FIT_SIGNATURE)
int bootm_host_load_images(const void *fit, int cfg_noffset);
#endif
int boot_selected_os(int argc, char *const argv[], int state,
bootm_headers_t *images, boot_os_fn *boot_fn);
ulong bootm_disable_interrupts(void);
/* This is a special function used by booti/bootz */
int bootm_find_images(int flag, int argc, char *const argv[], ulong start,
ulong size);
int do_bootm_states(struct cmd_tbl *cmdtp, int flag, int argc,
char *const argv[], int states, bootm_headers_t *images,
int boot_progress);
void arch_preboot_os(void);
/*
* boards should define this to disable devices when EFI exits from boot
* services.
*
* TODO(sjg@chromium.org>): Update this to use driver model's device_remove().
*/
void board_quiesce_devices(void);
/**
* switch_to_non_secure_mode() - switch to non-secure mode
*/
void switch_to_non_secure_mode(void);
/* Flags to control bootm_process_cmdline() */
enum bootm_cmdline_t {
BOOTM_CL_SILENT = 1 << 0, /* Do silent console processing */
BOOTM_CL_SUBST = 1 << 1, /* Do substitution */
BOOTM_CL_ALL = 3, /* All substitutions */
};
/**
* arch_preboot_os() - arch specific configuration before booting
*/
void arch_preboot_os(void);
/**
* board_preboot_os() - board specific configuration before booting
*/
void board_preboot_os(void);
/*
* bootm_process_cmdline() - Process fix-ups for the command line
*
* This handles:
*
* - making Linux boot silently if requested ('silent_linux' envvar)
* - performing substitutions in the command line ('bootargs_subst' envvar)
*
* @maxlen must provide enough space for the string being processed plus the
* resulting string
*
* @buf: buffer holding commandline string to adjust
* @maxlen: Maximum length of buffer at @buf (including \0)
* @flags: Flags to control what happens (see bootm_cmdline_t)
* @return 0 if OK, -ENOMEM if out of memory, -ENOSPC if the commandline is too
* long
*/
int bootm_process_cmdline(char *buf, int maxlen, int flags);
/**
* bootm_process_cmdline_env() - Process fix-ups for the command line
*
* Updates the 'bootargs' envvar as required. This handles:
*
* - making Linux boot silently if requested ('silent_linux' envvar)
* - performing substitutions in the command line ('bootargs_subst' envvar)
*
* @flags: Flags to control what happens (see bootm_cmdline_t)
* @return 0 if OK, -ENOMEM if out of memory
*/
int bootm_process_cmdline_env(int flags);
#endif