doc/README.sandbox

   1 /*
   2  * Copyright (c) 2014 The Chromium OS Authors.
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 Native Execution of U-Boot
   8 ==========================
   9
  10 The 'sandbox' architecture is designed to allow U-Boot to run under Linux on
  11 almost any hardware. To achieve this it builds U-Boot (so far as possible)
  12 as a normal C application with a main() and normal C libraries.
  13
  14 All of U-Boot's architecture-specific code therefore cannot be built as part
  15 of the sandbox U-Boot. The purpose of running U-Boot under Linux is to test
  16 all the generic code, not specific to any one architecture. The idea is to
  17 create unit tests which we can run to test this upper level code.
  18
  19 CONFIG_SANDBOX is defined when building a native board.
  20
  21 The chosen vendor and board names are also 'sandbox', so there is a single
  22 board in board/sandbox/sandbox.
  23
  24 CONFIG_SANDBOX_BIG_ENDIAN should be defined when running on big-endian
  25 machines.
  26
  27 Note that standalone/API support is not available at present.
  28
  29
  30 Basic Operation
  31 ---------------
  32
  33 To run sandbox U-Boot use something like:
  34
  35    make sandbox_config all
  36    ./u-boot
  37
  38 Note:
  39    If you get errors about 'sdl-config: Command not found' you may need to
  40    install libsdl1.2-dev or similar to get SDL support. Alternatively you can
  41    build sandbox without SDL (i.e. no display/keyboard support) by removing
  42    the CONFIG_SANDBOX_SDL line in include/configs/sandbox.h or using:
  43
  44       make sandbox_config all NO_SDL=1
  45       ./u-boot
  46
  47
  48 U-Boot will start on your computer, showing a sandbox emulation of the serial
  49 console:
  50
  51
  52 U-Boot 2014.04 (Mar 20 2014 - 19:06:00)
  53
  54 DRAM:  128 MiB
  55 Using default environment
  56
  57 In:    serial
  58 Out:   lcd
  59 Err:   lcd
  60 =>
  61
  62 You can issue commands as your would normally. If the command you want is
  63 not supported you can add it to include/configs/sandbox.h.
  64
  65 To exit, type 'reset' or press Ctrl-C.
  66
  67
  68 Console / LCD support
  69 ---------------------
  70
  71 Assuming that CONFIG_SANDBOX_SDL is defined when building, you can run the
  72 sandbox with LCD and keyboard emulation, using something like:
  73
  74    ./u-boot -d u-boot.dtb -l
  75
  76 This will start U-Boot with a window showing the contents of the LCD. If
  77 that window has the focus then you will be able to type commands as you
  78 would on the console. You can adjust the display settings in the device
  79 tree file - see arch/sandbox/dts/sandbox.dts.
  80
  81
  82 Command-line Options
  83 --------------------
  84
  85 Various options are available, mostly for test purposes. Use -h to see
  86 available options. Some of these are described below.
  87
  88 The terminal is normally in what is called 'raw-with-sigs' mode. This means
  89 that you can use arrow keys for command editing and history, but if you
  90 press Ctrl-C, U-Boot will exit instead of handling this as a keypress.
  91
  92 Other options are 'raw' (so Ctrl-C is handled within U-Boot) and 'cooked'
  93 (where the terminal is in cooked mode and cursor keys will not work, Ctrl-C
  94 will exit).
  95
  96 As mentioned above, -l causes the LCD emulation window to be shown.
  97
  98 A device tree binary file can be provided with -d. If you edit the source
  99 (it is stored at arch/sandbox/dts/sandbox.dts) you must rebuild U-Boot to
 100 recreate the binary file.
 101
 102 To execute commands directly, use the -c option. You can specify a single
 103 command, or multiple commands separated by a semicolon, as is normal in
 104 U-Boot. Be careful with quoting as the shall will normally process and
 105 swallow quotes. When -c is used, U-Boot exists after the command is complete,
 106 but you can force it to go to interactive mode instead with -i.
 107
 108
 109 Memory Emulation
 110 ----------------
 111
 112 Memory emulation is supported, with the size set by CONFIG_SYS_SDRAM_SIZE.
 113 The -m option can be used to read memory from a file on start-up and write
 114 it when shutting down. This allows preserving of memory contents across
 115 test runs. You can tell U-Boot to remove the memory file after it is read
 116 (on start-up) with the --rm_memory option.
 117
 118 To access U-Boot's emulated memory within the code, use map_sysmem(). This
 119 function is used throughout U-Boot to ensure that emulated memory is used
 120 rather than the U-Boot application memory. This provides memory starting
 121 at 0 and extending to the size of the emulation.
 122
 123
 124 Storing State
 125 -------------
 126
 127 With sandbox you can write drivers which emulate the operation of drivers on
 128 real devices. Some of these drivers may want to record state which is
 129 preserved across U-Boot runs. This is particularly useful for testing. For
 130 example, the contents of a SPI flash chip should not disappear just because
 131 U-Boot exits.
 132
 133 State is stored in a device tree file in a simple format which is driver-
 134 specific. You then use the -s option to specify the state file. Use -r to
 135 make U-Boot read the state on start-up (otherwise it starts empty) and -w
 136 to write it on exit (otherwise the stored state is left unchanged and any
 137 changes U-Boot made will be lost). You can also use -n to tell U-Boot to
 138 ignore any problems with missing state. This is useful when first running
 139 since the state file will be empty.
 140
 141 The device tree file has one node for each driver - the driver can store
 142 whatever properties it likes in there. See 'Writing Sandbox Drivers' below
 143 for more details on how to get drivers to read and write their state.
 144
 145
 146 Running and Booting
 147 -------------------
 148
 149 Since there is no machine architecture, sandbox U-Boot cannot actually boot
 150 a kernel, but it does support the bootm command. Filesystems, memory
 151 commands, hashing, FIT images, verified boot and many other features are
 152 supported.
 153
 154 When 'bootm' runs a kernel, sandbox will exit, as U-Boot does on a real
 155 machine. Of course in this case, no kernel is run.
 156
 157 It is also possible to tell U-Boot that it has jumped from a temporary
 158 previous U-Boot binary, with the -j option. That binary is automatically
 159 removed by the U-Boot that gets the -j option. This allows you to write
 160 tests which emulate the action of chain-loading U-Boot, typically used in
 161 a situation where a second 'updatable' U-Boot is stored on your board. It
 162 is very risky to overwrite or upgrade the only U-Boot on a board, since a
 163 power or other failure will brick the board and require return to the
 164 manufacturer in the case of a consumer device.
 165
 166
 167 Supported Drivers
 168 -----------------
 169
 170 U-Boot sandbox supports these emulations:
 171
 172 - Block devices
 173 - Chrome OS EC
 174 - GPIO
 175 - Host filesystem (access files on the host from within U-Boot)
 176 - Keyboard (Chrome OS)
 177 - LCD
 178 - Serial (for console only)
 179 - Sound (incomplete - see sandbox_sdl_sound_init() for details)
 180 - SPI
 181 - SPI flash
 182 - TPM (Trusted Platform Module)
 183
 184 Notable omissions are networking and I2C.
 185
 186 A wide range of commands is implemented. Filesystems which use a block
 187 device are supported.
 188
 189 Also sandbox uses generic board (CONFIG_SYS_GENERIC_BOARD) and supports
 190 driver model (CONFIG_DM) and associated commands.
 191
 192
 193 SPI Emulation
 194 -------------
 195
 196 Sandbox supports SPI and SPI flash emulation.
 197
 198 This is controlled by the spi_sf argument, the format of which is:
 199
 200    bus:cs:device:file
 201
 202    bus    - SPI bus number
 203    cs     - SPI chip select number
 204    device - SPI device emulation name
 205    file   - File on disk containing the data
 206
 207 For example:
 208
 209  dd if=/dev/zero of=spi.bin bs=1M count=4
 210  ./u-boot --spi_sf 0:0:M25P16:spi.bin
 211
 212 With this setup you can issue SPI flash commands as normal:
 213
 214 =>sf probe
 215 SF: Detected M25P16 with page size 64 KiB, total 2 MiB
 216 =>sf read 0 0 10000
 217 SF: 65536 bytes @ 0x0 Read: OK
 218 =>
 219
 220 Since this is a full SPI emulation (rather than just flash), you can
 221 also use low-level SPI commands:
 222
 223 =>sspi 0:0 32 9f
 224 FF202015
 225
 226 This is issuing a READ_ID command and getting back 20 (ST Micro) part
 227 0x2015 (the M25P16).
 228
 229 Drivers are connected to a particular bus/cs using sandbox's state
 230 structure (see the 'spi' member). A set of operations must be provided
 231 for each driver.
 232
 233
 234 Configuration settings for the curious are:
 235
 236 CONFIG_SANDBOX_SPI_MAX_BUS
 237         The maximum number of SPI buses supported by the driver (default 1).
 238
 239 CONFIG_SANDBOX_SPI_MAX_CS
 240         The maximum number of chip selects supported by the driver
 241         (default 10).
 242
 243 CONFIG_SPI_IDLE_VAL
 244         The idle value on the SPI bus
 245
 246
 247 Writing Sandbox Drivers
 248 -----------------------
 249
 250 Generally you should put your driver in a file containing the word 'sandbox'
 251 and put it in the same directory as other drivers of its type. You can then
 252 implement the same hooks as the other drivers.
 253
 254 To access U-Boot's emulated memory, use map_sysmem() as mentioned above.
 255
 256 If your driver needs to store configuration or state (such as SPI flash
 257 contents or emulated chip registers), you can use the device tree as
 258 described above. Define handlers for this with the SANDBOX_STATE_IO macro.
 259 See arch/sandbox/include/asm/state.h for documentation. In short you provide
 260 a node name, compatible string and functions to read and write the state.
 261 Since writing the state can expand the device tree, you may need to use
 262 state_setprop() which does this automatically and avoids running out of
 263 space. See existing code for examples.
 264
 265
 266 Testing
 267 -------
 268
 269 U-Boot sandbox can be used to run various tests, mostly in the test/
 270 directory. These include:
 271
 272   command_ut
 273      - Unit tests for command parsing and handling
 274   compression
 275      - Unit tests for U-Boot's compression algorithms, useful for
 276        security checking. It supports gzip, bzip2, lzma and lzo.
 277   driver model
 278      - test/dm/test-dm.sh to run these.
 279   image
 280      - Unit tests for images:
 281           test/image/test-imagetools.sh - multi-file images
 282           test/image/test-fit.py        - FIT images
 283   tracing
 284      - test/trace/test-trace.sh tests the tracing system (see README.trace)
 285   verified boot
 286       - See test/vboot/vboot_test.sh for this
 287
 288 If you change or enhance any of the above subsystems, you shold write or
 289 expand a test and include it with your patch series submission. Test
 290 coverage in U-Boot is limited, as we need to work to improve it.
 291
 292 Note that many of these tests are implemented as commands which you can
 293 run natively on your board if desired (and enabled).
 294
 295 It would be useful to have a central script to run all of these.
 296
 297 --
 298 Simon Glass <sjg@chromium.org>
 299 Updated 22-Mar-14