doc/usage/cmd/read.rst

   1 .. SPDX-License-Identifier: GPL-2.0-or-later:
   2
   3 read and write commands
   4 =======================
   5
   6 Synopsis
   7 --------
   8
   9 ::
  10
  11     read <interface> <dev[:part|#partname]> <addr> <blk#> <cnt>
  12     write <interface> <dev[:part|#partname]> <addr> <blk#> <cnt>
  13
  14 The read and write commands can be used for raw access to data in
  15 block devices (or partitions therein), i.e. without going through a
  16 file system.
  17
  18 read
  19 ----
  20
  21 The block device is specified using the <interface> (e.g. "mmc") and
  22 <dev> parameters. If the block device has a partition table, one can
  23 optionally specify a partition number (using the :part syntax) or
  24 partition name (using the #partname syntax). The command then reads
  25 the <cnt> blocks of data starting at block number <blk#> of the given
  26 device/partition to the memory address <addr>.
  27
  28 write
  29 -----
  30
  31 The write command is completely equivalent to the read command, except
  32 of course that the transfer direction is reversed.
  33
  34 Examples
  35 --------
  36
  37     # Read 2 MiB from partition 3 of mmc device 2 to $loadaddr
  38     read mmc 2.3 $loadaddr 0 0x1000
  39
  40     # Read 16 MiB from the partition named 'kernel' of mmc device 1 to $loadaddr
  41     read mmc 1#kernel $loadaddr 0 0x8000
  42
  43     # Write to the third sector of the partition named 'bootdata' of mmc device 0
  44     write mmc 0#bootdata $loadaddr 2 1