qemu/docs/generic-loader.txt
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   1Copyright (c) 2016 Xilinx Inc.
   2
   3This work is licensed under the terms of the GNU GPL, version 2 or later.  See
   4the COPYING file in the top-level directory.
   5
   6
   7The 'loader' device allows the user to load multiple images or values into
   8QEMU at startup.
   9
  10Loading Data into Memory Values
  11-------------------------------
  12The loader device allows memory values to be set from the command line. This
  13can be done by following the syntax below:
  14
  15     -device loader,addr=<addr>,data=<data>,data-len=<data-len>
  16                   [,data-be=<data-be>][,cpu-num=<cpu-num>]
  17
  18    <addr>      - The address to store the data in.
  19    <data>      - The value to be written to the address. The maximum size of
  20                  the data is 8 bytes.
  21    <data-len>  - The length of the data in bytes. This argument must be
  22                  included if the data argument is.
  23    <data-be>   - Set to true if the data to be stored on the guest should be
  24                  written as big endian data. The default is to write little
  25                  endian data.
  26    <cpu-num>   - The number of the CPU's address space where the data should
  27                  be loaded. If not specified the address space of the first
  28                  CPU is used.
  29
  30All values are parsed using the standard QemuOps parsing. This allows the user
  31to specify any values in any format supported. By default the values
  32will be parsed as decimal. To use hex values the user should prefix the number
  33with a '0x'.
  34
  35An example of loading value 0x8000000e to address 0xfd1a0104 is:
  36    -device loader,addr=0xfd1a0104,data=0x8000000e,data-len=4
  37
  38Setting a CPU's Program Counter
  39-------------------------------
  40The loader device allows the CPU's PC to be set from the command line. This
  41can be done by following the syntax below:
  42
  43     -device loader,addr=<addr>,cpu-num=<cpu-num>
  44
  45    <addr>      - The value to use as the CPU's PC.
  46    <cpu-num>   - The number of the CPU whose PC should be set to the
  47                  specified value.
  48
  49All values are parsed using the standard QemuOps parsing. This allows the user
  50to specify any values in any format supported. By default the values
  51will be parsed as decimal. To use hex values the user should prefix the number
  52with a '0x'.
  53
  54An example of setting CPU 0's PC to 0x8000 is:
  55    -device loader,addr=0x8000,cpu-num=0
  56
  57Loading Files
  58-------------
  59The loader device also allows files to be loaded into memory. It can load raw
  60files and ELF executable files.  Raw files are loaded verbatim.  ELF executable
  61files are loaded by an ELF loader.  The syntax is shown below:
  62
  63    -device loader,file=<file>[,addr=<addr>][,cpu-num=<cpu-num>][,force-raw=<raw>]
  64
  65    <file>      - A file to be loaded into memory
  66    <addr>      - The addr in memory that the file should be loaded. This is
  67                  ignored if you are using an ELF (unless force-raw is true).
  68                  This is required if you aren't loading an ELF.
  69    <cpu-num>   - This specifies the CPU that should be used. This is an
  70                  optional argument and will cause the CPU's PC to be set to
  71                  where the image is stored or in the case of an ELF file to
  72                  the value in the header. This option should only be used
  73                  for the boot image.
  74                  This will also cause the image to be written to the specified
  75                  CPU's address space. If not specified, the default is CPU 0.
  76    <force-raw> - Setting force-raw=on forces the file to be treated as a raw
  77                  image.  This can be used to load ELF files as if they were raw.
  78
  79All values are parsed using the standard QemuOps parsing. This allows the user
  80to specify any values in any format supported. By default the values
  81will be parsed as decimal. To use hex values the user should prefix the number
  82with a '0x'.
  83
  84An example of loading an ELF file which CPU0 will boot is shown below:
  85    -device loader,file=./images/boot.elf,cpu-num=0
  86
  87Restrictions and ToDos
  88----------------------
  89 - At the moment it is just assumed that if you specify a cpu-num then you
  90   want to set the PC as well. This might not always be the case. In future
  91   the internal state 'set_pc' (which exists in the generic loader now) should
  92   be exposed to the user so that they can choose if the PC is set or not.
  93