u-boot/doc/usage/fatload.rst
Heinrich Schuchardt 57b98efa16 doc: describe fatload command
Man-page for fatload command.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2022-02-26 07:37:00 +01:00

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.. SPDX-License-Identifier: GPL-2.0+:
fatload command
===============
Synopsis
--------
::
fatload <interface> [<dev[:part]> [<addr> [<filename> [bytes [pos]]]]]
Description
-----------
The fatload command is used to read a file from a FAT filesystem into memory.
You can always use the :doc:`load command <load>` instead.
The number of transferred bytes is saved in the environment variable filesize.
The load address is saved in the environment variable fileaddr.
interface
interface for accessing the block device (mmc, sata, scsi, usb, ....)
dev
device number
part
partition number, defaults to 0 (whole device)
addr
load address, defaults to environment variable loadaddr or if loadaddr is
not set to configuration variable CONFIG_SYS_LOAD_ADDR
filename
path to file, defaults to environment variable bootfile
bytes
maximum number of bytes to load
pos
number of bytes to skip
addr, bytes, pos are hexadecimal numbers.
If either 'pos' or 'bytes' are not aligned according to the minimum alignment
requirement for DMA transfer (ARCH_DMA_MINALIGN) additional buffering will be
used, a misaligned buffer warning will be printed, and performance will suffer
for the load.
Example
-------
::
=> fatload mmc 0:1 ${kernel_addr_r} snp.efi
149280 bytes read in 11 ms (12.9 MiB/s)
=>
=> fatload mmc 0:1 ${kernel_addr_r} snp.efi 1000000
149280 bytes read in 9 ms (15.8 MiB/s)
=>
=> fatload mmc 0:1 ${kernel_addr_r} snp.efi 1000000 100
149024 bytes read in 10 ms (14.2 MiB/s)
=>
=> fatload mmc 0:1 ${kernel_addr_r} snp.efi 10
16 bytes read in 1 ms (15.6 KiB/s)
=>
Configuration
-------------
The fatload command is only available if CONFIG_CMD_FAT=y.
Return value
------------
The return value $? is set to 0 (true) if the file was successfully loaded
even if the number of bytes is less then the specified length.
If an error occurs, the return value $? is set to 1 (false).