board/sandbox/README.sandbox - github/trini/u-boot - Gitiles

 /* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (c) 2014 The Chromium OS Authors.
  */

 Native Execution of U-Boot
 ==========================

 The 'sandbox' architecture is designed to allow U-Boot to run under Linux on
 almost any hardware. To achieve this it builds U-Boot (so far as possible)
 as a normal C application with a main() and normal C libraries.

 All of U-Boot's architecture-specific code therefore cannot be built as part
 of the sandbox U-Boot. The purpose of running U-Boot under Linux is to test
 all the generic code, not specific to any one architecture. The idea is to
 create unit tests which we can run to test this upper level code.

 CONFIG_SANDBOX is defined when building a native board.

 The board name is 'sandbox' but the vendor name is unset, so there is a
 single board in board/sandbox.

 CONFIG_SANDBOX_BIG_ENDIAN should be defined when running on big-endian
 machines.

 There are two versions of the sandbox: One using 32-bit-wide integers, and one
 using 64-bit-wide integers. The 32-bit version can be build and run on either
 32 or 64-bit hosts by either selecting or deselecting CONFIG_SANDBOX_32BIT; by
 default, the sandbox it built for a 32-bit host. The sandbox using 64-bit-wide
 integers can only be built on 64-bit hosts.

 Note that standalone/API support is not available at present.


 Basic Operation
 ---------------

 To run sandbox U-Boot use something like:

    make sandbox_defconfig all
    ./u-boot

 Note:
    If you get errors about 'sdl-config: Command not found' you may need to
    install libsdl1.2-dev or similar to get SDL support. Alternatively you can
    build sandbox without SDL (i.e. no display/keyboard support) by removing
    the CONFIG_SANDBOX_SDL line in include/configs/sandbox.h or using:

       make sandbox_defconfig all NO_SDL=1
       ./u-boot

 U-Boot will start on your computer, showing a sandbox emulation of the serial
 console:


 U-Boot 2014.04 (Mar 20 2014 - 19:06:00)

 DRAM:  128 MiB
 Using default environment

 In:    serial
 Out:   lcd
 Err:   lcd
 =>

 You can issue commands as your would normally. If the command you want is
 not supported you can add it to include/configs/sandbox.h.

 To exit, type 'reset' or press Ctrl-C.


 Console / LCD support
 ---------------------

 Assuming that CONFIG_SANDBOX_SDL is defined when building, you can run the
 sandbox with LCD and keyboard emulation, using something like:

    ./u-boot -d u-boot.dtb -l

 This will start U-Boot with a window showing the contents of the LCD. If
 that window has the focus then you will be able to type commands as you
 would on the console. You can adjust the display settings in the device
 tree file - see arch/sandbox/dts/sandbox.dts.


 Command-line Options
 --------------------

 Various options are available, mostly for test purposes. Use -h to see
 available options. Some of these are described below.

 The terminal is normally in what is called 'raw-with-sigs' mode. This means
 that you can use arrow keys for command editing and history, but if you
 press Ctrl-C, U-Boot will exit instead of handling this as a keypress.

 Other options are 'raw' (so Ctrl-C is handled within U-Boot) and 'cooked'
 (where the terminal is in cooked mode and cursor keys will not work, Ctrl-C
 will exit).

 As mentioned above, -l causes the LCD emulation window to be shown.

 A device tree binary file can be provided with -d. If you edit the source
 (it is stored at arch/sandbox/dts/sandbox.dts) you must rebuild U-Boot to
 recreate the binary file.

 To execute commands directly, use the -c option. You can specify a single
 command, or multiple commands separated by a semicolon, as is normal in
 U-Boot. Be careful with quoting as the shell will normally process and
 swallow quotes. When -c is used, U-Boot exits after the command is complete,
 but you can force it to go to interactive mode instead with -i.


 Memory Emulation
 ----------------

 Memory emulation is supported, with the size set by CONFIG_SYS_SDRAM_SIZE.
 The -m option can be used to read memory from a file on start-up and write
 it when shutting down. This allows preserving of memory contents across
 test runs. You can tell U-Boot to remove the memory file after it is read
 (on start-up) with the --rm_memory option.

 To access U-Boot's emulated memory within the code, use map_sysmem(). This
 function is used throughout U-Boot to ensure that emulated memory is used
 rather than the U-Boot application memory. This provides memory starting
 at 0 and extending to the size of the emulation.


 Storing State
 -------------

 With sandbox you can write drivers which emulate the operation of drivers on
 real devices. Some of these drivers may want to record state which is
 preserved across U-Boot runs. This is particularly useful for testing. For
 example, the contents of a SPI flash chip should not disappear just because
 U-Boot exits.

 State is stored in a device tree file in a simple format which is driver-
 specific. You then use the -s option to specify the state file. Use -r to
 make U-Boot read the state on start-up (otherwise it starts empty) and -w
 to write it on exit (otherwise the stored state is left unchanged and any
 changes U-Boot made will be lost). You can also use -n to tell U-Boot to
 ignore any problems with missing state. This is useful when first running
 since the state file will be empty.

 The device tree file has one node for each driver - the driver can store
 whatever properties it likes in there. See 'Writing Sandbox Drivers' below
 for more details on how to get drivers to read and write their state.


 Running and Booting
 -------------------

 Since there is no machine architecture, sandbox U-Boot cannot actually boot
 a kernel, but it does support the bootm command. Filesystems, memory
 commands, hashing, FIT images, verified boot and many other features are
 supported.

 When 'bootm' runs a kernel, sandbox will exit, as U-Boot does on a real
 machine. Of course in this case, no kernel is run.

 It is also possible to tell U-Boot that it has jumped from a temporary
 previous U-Boot binary, with the -j option. That binary is automatically
 removed by the U-Boot that gets the -j option. This allows you to write
 tests which emulate the action of chain-loading U-Boot, typically used in
 a situation where a second 'updatable' U-Boot is stored on your board. It
 is very risky to overwrite or upgrade the only U-Boot on a board, since a
 power or other failure will brick the board and require return to the
 manufacturer in the case of a consumer device.


 Supported Drivers
 -----------------

 U-Boot sandbox supports these emulations:

 - Block devices
 - Chrome OS EC
 - GPIO
 - Host filesystem (access files on the host from within U-Boot)
 - I2C
 - Keyboard (Chrome OS)
 - LCD
 - Network
 - Serial (for console only)
 - Sound (incomplete - see sandbox_sdl_sound_init() for details)
 - SPI
 - SPI flash
 - TPM (Trusted Platform Module)

 A wide range of commands are implemented. Filesystems which use a block
 device are supported.

 Also sandbox supports driver model (CONFIG_DM) and associated commands.


 Sandbox Variants
 ----------------

 There are unfortunately quite a few variants at present:

 sandbox - should be used for most tests
 sandbox64 - special build that forces a 64-bit host
 sandbox_flattree - builds with dev_read_...() functions defined as inline.
     We need this build so that we can test those inline functions, and we
     cannot build with both the inline functions and the non-inline functions
     since they are named the same.
 sandbox_noblk - builds without CONFIG_BLK, which means the legacy block
     drivers are used. We cannot use both the legacy and driver-model block
     drivers since they implement the same functions
 sandbox_spl - builds sandbox with SPL support, so you can run spl/u-boot-spl
     and it will start up and then load ./u-boot. It is also possible to
     run ./u-boot directly.

 Of these sandbox_noblk can be removed once CONFIG_BLK is used everwhere, and
 sandbox_spl can probably be removed since it is a superset of sandbox.

 Most of the config options should be identical between these variants.


 Linux RAW Networking Bridge
 ---------------------------

 The sandbox_eth_raw driver bridges traffic between the bottom of the network
 stack and the RAW sockets API in Linux. This allows much of the U-Boot network
 functionality to be tested in sandbox against real network traffic.

 For Ethernet network adapters, the bridge utilizes the RAW AF_PACKET API.  This
 is needed to get access to the lowest level of the network stack in Linux. This
 means that all of the Ethernet frame is included. This allows the U-Boot network
 stack to be fully used. In other words, nothing about the Linux network stack is
 involved in forming the packets that end up on the wire. To receive the
 responses to packets sent from U-Boot the network interface has to be set to
 promiscuous mode so that the network card won't filter out packets not destined
 for its configured (on Linux) MAC address.

 The RAW sockets Ethernet API requires elevated privileges in Linux. You can
 either run as root, or you can add the capability needed like so:

 sudo /sbin/setcap "CAP_NET_RAW+ep" /path/to/u-boot

 The default device tree for sandbox includes an entry for eth0 on the sandbox
 host machine whose alias is "eth1". The following are a few examples of network
 operations being tested on the eth0 interface.

 sudo /path/to/u-boot -D

 DHCP
 ....

 set autoload no
 set ethact eth1
 dhcp

 PING
 ....

 set autoload no
 set ethact eth1
 dhcp
 ping $gatewayip

 TFTP
 ....

 set autoload no
 set ethact eth1
 dhcp
 set serverip WWW.XXX.YYY.ZZZ
 tftpboot u-boot.bin

 The bridge also supports (to a lesser extent) the localhost interface, 'lo'.

 The 'lo' interface cannot use the RAW AF_PACKET API because the lo interface
 doesn't support Ethernet-level traffic. It is a higher-level interface that is
 expected only to be used at the AF_INET level of the API. As such, the most raw
 we can get on that interface is the RAW AF_INET API on UDP. This allows us to
 set the IP_HDRINCL option to include everything except the Ethernet header in
 the packets we send and receive.

 Because only UDP is supported, ICMP traffic will not work, so expect that ping
 commands will time out.

 The default device tree for sandbox includes an entry for lo on the sandbox
 host machine whose alias is "eth5". The following is an example of a network
 operation being tested on the lo interface.

 TFTP
 ....

 set ethact eth5
 tftpboot u-boot.bin


 SPI Emulation
 -------------

 Sandbox supports SPI and SPI flash emulation.

 This is controlled by the spi_sf argument, the format of which is:

    bus:cs:device:file

    bus    - SPI bus number
    cs     - SPI chip select number
    device - SPI device emulation name
    file   - File on disk containing the data

 For example:

  dd if=/dev/zero of=spi.bin bs=1M count=4
  ./u-boot --spi_sf 0:0:M25P16:spi.bin

 With this setup you can issue SPI flash commands as normal:

 =>sf probe
 SF: Detected M25P16 with page size 64 KiB, total 2 MiB
 =>sf read 0 0 10000
 SF: 65536 bytes @ 0x0 Read: OK
 =>

 Since this is a full SPI emulation (rather than just flash), you can
 also use low-level SPI commands:

 =>sspi 0:0 32 9f
 FF202015

 This is issuing a READ_ID command and getting back 20 (ST Micro) part
 0x2015 (the M25P16).

 Drivers are connected to a particular bus/cs using sandbox's state
 structure (see the 'spi' member). A set of operations must be provided
 for each driver.


 Configuration settings for the curious are:

 CONFIG_SANDBOX_SPI_MAX_BUS
 	The maximum number of SPI buses supported by the driver (default 1).

 CONFIG_SANDBOX_SPI_MAX_CS
 	The maximum number of chip selects supported by the driver
 	(default 10).

 CONFIG_SPI_IDLE_VAL
 	The idle value on the SPI bus


 Block Device Emulation
 ----------------------

 U-Boot can use raw disk images for block device emulation. To e.g. list
 the contents of the root directory on the second partion of the image
 "disk.raw", you can use the following commands:

 =>host bind 0 ./disk.raw
 =>ls host 0:2

 A disk image can be created using the following commands:

 $> truncate -s 1200M ./disk.raw
 $> echo -e "label: gpt\n,64M,U\n,,L" | /usr/sbin/sgdisk  ./disk.raw
 $> lodev=`sudo losetup -P -f --show ./disk.raw`
 $> sudo mkfs.vfat -n EFI -v ${lodev}p1
 $> sudo mkfs.ext4 -L ROOT -v ${lodev}p2

 or utilize the device described in test/py/make_test_disk.py:

    #!/usr/bin/python
    import make_test_disk
    make_test_disk.makeDisk()

 Writing Sandbox Drivers
 -----------------------

 Generally you should put your driver in a file containing the word 'sandbox'
 and put it in the same directory as other drivers of its type. You can then
 implement the same hooks as the other drivers.

 To access U-Boot's emulated memory, use map_sysmem() as mentioned above.

 If your driver needs to store configuration or state (such as SPI flash
 contents or emulated chip registers), you can use the device tree as
 described above. Define handlers for this with the SANDBOX_STATE_IO macro.
 See arch/sandbox/include/asm/state.h for documentation. In short you provide
 a node name, compatible string and functions to read and write the state.
 Since writing the state can expand the device tree, you may need to use
 state_setprop() which does this automatically and avoids running out of
 space. See existing code for examples.


 Testing
 -------

 U-Boot sandbox can be used to run various tests, mostly in the test/
 directory. These include:

   command_ut
      - Unit tests for command parsing and handling
   compression
      - Unit tests for U-Boot's compression algorithms, useful for
        security checking. It supports gzip, bzip2, lzma and lzo.
   driver model
      - Run this pytest
 	  ./test/py/test.py --bd sandbox --build -k ut_dm -v
   image
      - Unit tests for images:
           test/image/test-imagetools.sh - multi-file images
           test/image/test-fit.py        - FIT images
   tracing
      - test/trace/test-trace.sh tests the tracing system (see README.trace)
   verified boot
       - See test/vboot/vboot_test.sh for this

 If you change or enhance any of the above subsystems, you shold write or
 expand a test and include it with your patch series submission. Test
 coverage in U-Boot is limited, as we need to work to improve it.

 Note that many of these tests are implemented as commands which you can
 run natively on your board if desired (and enabled).

 It would be useful to have a central script to run all of these.

 --
 Simon Glass <sjg@chromium.org>
 Updated 22-Mar-14
	/* SPDX-License-Identifier: GPL-2.0+ */
	/*
	* Copyright (c) 2014 The Chromium OS Authors.
	*/

	Native Execution of U-Boot
	==========================

	The 'sandbox' architecture is designed to allow U-Boot to run under Linux on
	almost any hardware. To achieve this it builds U-Boot (so far as possible)
	as a normal C application with a main() and normal C libraries.

	All of U-Boot's architecture-specific code therefore cannot be built as part
	of the sandbox U-Boot. The purpose of running U-Boot under Linux is to test
	all the generic code, not specific to any one architecture. The idea is to
	create unit tests which we can run to test this upper level code.

	CONFIG_SANDBOX is defined when building a native board.

	The board name is 'sandbox' but the vendor name is unset, so there is a
	single board in board/sandbox.

	CONFIG_SANDBOX_BIG_ENDIAN should be defined when running on big-endian
	machines.

	There are two versions of the sandbox: One using 32-bit-wide integers, and one
	using 64-bit-wide integers. The 32-bit version can be build and run on either
	32 or 64-bit hosts by either selecting or deselecting CONFIG_SANDBOX_32BIT; by
	default, the sandbox it built for a 32-bit host. The sandbox using 64-bit-wide
	integers can only be built on 64-bit hosts.

	Note that standalone/API support is not available at present.


	Basic Operation
	---------------

	To run sandbox U-Boot use something like:

	make sandbox_defconfig all
	./u-boot

	Note:
	If you get errors about 'sdl-config: Command not found' you may need to
	install libsdl1.2-dev or similar to get SDL support. Alternatively you can
	build sandbox without SDL (i.e. no display/keyboard support) by removing
	the CONFIG_SANDBOX_SDL line in include/configs/sandbox.h or using:

	make sandbox_defconfig all NO_SDL=1
	./u-boot

	U-Boot will start on your computer, showing a sandbox emulation of the serial
	console:


	U-Boot 2014.04 (Mar 20 2014 - 19:06:00)

	DRAM: 128 MiB
	Using default environment

	In: serial
	Out: lcd
	Err: lcd
	=>

	You can issue commands as your would normally. If the command you want is
	not supported you can add it to include/configs/sandbox.h.

	To exit, type 'reset' or press Ctrl-C.


	Console / LCD support
	---------------------

	Assuming that CONFIG_SANDBOX_SDL is defined when building, you can run the
	sandbox with LCD and keyboard emulation, using something like:

	./u-boot -d u-boot.dtb -l

	This will start U-Boot with a window showing the contents of the LCD. If
	that window has the focus then you will be able to type commands as you
	would on the console. You can adjust the display settings in the device
	tree file - see arch/sandbox/dts/sandbox.dts.


	Command-line Options
	--------------------

	Various options are available, mostly for test purposes. Use -h to see
	available options. Some of these are described below.

	The terminal is normally in what is called 'raw-with-sigs' mode. This means
	that you can use arrow keys for command editing and history, but if you
	press Ctrl-C, U-Boot will exit instead of handling this as a keypress.

	Other options are 'raw' (so Ctrl-C is handled within U-Boot) and 'cooked'
	(where the terminal is in cooked mode and cursor keys will not work, Ctrl-C
	will exit).

	As mentioned above, -l causes the LCD emulation window to be shown.

	A device tree binary file can be provided with -d. If you edit the source
	(it is stored at arch/sandbox/dts/sandbox.dts) you must rebuild U-Boot to
	recreate the binary file.

	To execute commands directly, use the -c option. You can specify a single
	command, or multiple commands separated by a semicolon, as is normal in
	U-Boot. Be careful with quoting as the shell will normally process and
	swallow quotes. When -c is used, U-Boot exits after the command is complete,
	but you can force it to go to interactive mode instead with -i.


	Memory Emulation
	----------------

	Memory emulation is supported, with the size set by CONFIG_SYS_SDRAM_SIZE.
	The -m option can be used to read memory from a file on start-up and write
	it when shutting down. This allows preserving of memory contents across
	test runs. You can tell U-Boot to remove the memory file after it is read
	(on start-up) with the --rm_memory option.

	To access U-Boot's emulated memory within the code, use map_sysmem(). This
	function is used throughout U-Boot to ensure that emulated memory is used
	rather than the U-Boot application memory. This provides memory starting
	at 0 and extending to the size of the emulation.


	Storing State
	-------------

	With sandbox you can write drivers which emulate the operation of drivers on
	real devices. Some of these drivers may want to record state which is
	preserved across U-Boot runs. This is particularly useful for testing. For
	example, the contents of a SPI flash chip should not disappear just because
	U-Boot exits.

	State is stored in a device tree file in a simple format which is driver-
	specific. You then use the -s option to specify the state file. Use -r to
	make U-Boot read the state on start-up (otherwise it starts empty) and -w
	to write it on exit (otherwise the stored state is left unchanged and any
	changes U-Boot made will be lost). You can also use -n to tell U-Boot to
	ignore any problems with missing state. This is useful when first running
	since the state file will be empty.

	The device tree file has one node for each driver - the driver can store
	whatever properties it likes in there. See 'Writing Sandbox Drivers' below
	for more details on how to get drivers to read and write their state.


	Running and Booting
	-------------------

	Since there is no machine architecture, sandbox U-Boot cannot actually boot
	a kernel, but it does support the bootm command. Filesystems, memory
	commands, hashing, FIT images, verified boot and many other features are
	supported.

	When 'bootm' runs a kernel, sandbox will exit, as U-Boot does on a real
	machine. Of course in this case, no kernel is run.

	It is also possible to tell U-Boot that it has jumped from a temporary
	previous U-Boot binary, with the -j option. That binary is automatically
	removed by the U-Boot that gets the -j option. This allows you to write
	tests which emulate the action of chain-loading U-Boot, typically used in
	a situation where a second 'updatable' U-Boot is stored on your board. It
	is very risky to overwrite or upgrade the only U-Boot on a board, since a
	power or other failure will brick the board and require return to the
	manufacturer in the case of a consumer device.


	Supported Drivers
	-----------------

	U-Boot sandbox supports these emulations:

	- Block devices
	- Chrome OS EC
	- GPIO
	- Host filesystem (access files on the host from within U-Boot)
	- I2C
	- Keyboard (Chrome OS)
	- LCD
	- Network
	- Serial (for console only)
	- Sound (incomplete - see sandbox_sdl_sound_init() for details)
	- SPI
	- SPI flash
	- TPM (Trusted Platform Module)

	A wide range of commands are implemented. Filesystems which use a block
	device are supported.

	Also sandbox supports driver model (CONFIG_DM) and associated commands.


	Sandbox Variants
	----------------

	There are unfortunately quite a few variants at present:

	sandbox - should be used for most tests
	sandbox64 - special build that forces a 64-bit host
	sandbox_flattree - builds with dev_read_...() functions defined as inline.
	We need this build so that we can test those inline functions, and we
	cannot build with both the inline functions and the non-inline functions
	since they are named the same.
	sandbox_noblk - builds without CONFIG_BLK, which means the legacy block
	drivers are used. We cannot use both the legacy and driver-model block
	drivers since they implement the same functions
	sandbox_spl - builds sandbox with SPL support, so you can run spl/u-boot-spl
	and it will start up and then load ./u-boot. It is also possible to
	run ./u-boot directly.

	Of these sandbox_noblk can be removed once CONFIG_BLK is used everwhere, and
	sandbox_spl can probably be removed since it is a superset of sandbox.

	Most of the config options should be identical between these variants.


	Linux RAW Networking Bridge
	---------------------------

	The sandbox_eth_raw driver bridges traffic between the bottom of the network
	stack and the RAW sockets API in Linux. This allows much of the U-Boot network
	functionality to be tested in sandbox against real network traffic.

	For Ethernet network adapters, the bridge utilizes the RAW AF_PACKET API. This
	is needed to get access to the lowest level of the network stack in Linux. This
	means that all of the Ethernet frame is included. This allows the U-Boot network
	stack to be fully used. In other words, nothing about the Linux network stack is
	involved in forming the packets that end up on the wire. To receive the
	responses to packets sent from U-Boot the network interface has to be set to
	promiscuous mode so that the network card won't filter out packets not destined
	for its configured (on Linux) MAC address.

	The RAW sockets Ethernet API requires elevated privileges in Linux. You can
	either run as root, or you can add the capability needed like so:

	sudo /sbin/setcap "CAP_NET_RAW+ep" /path/to/u-boot

	The default device tree for sandbox includes an entry for eth0 on the sandbox
	host machine whose alias is "eth1". The following are a few examples of network
	operations being tested on the eth0 interface.

	sudo /path/to/u-boot -D

	DHCP
	....

	set autoload no
	set ethact eth1
	dhcp

	PING
	....

	set autoload no
	set ethact eth1
	dhcp
	ping $gatewayip

	TFTP
	....

	set autoload no
	set ethact eth1
	dhcp
	set serverip WWW.XXX.YYY.ZZZ
	tftpboot u-boot.bin

	The bridge also supports (to a lesser extent) the localhost interface, 'lo'.

	The 'lo' interface cannot use the RAW AF_PACKET API because the lo interface
	doesn't support Ethernet-level traffic. It is a higher-level interface that is
	expected only to be used at the AF_INET level of the API. As such, the most raw
	we can get on that interface is the RAW AF_INET API on UDP. This allows us to
	set the IP_HDRINCL option to include everything except the Ethernet header in
	the packets we send and receive.

	Because only UDP is supported, ICMP traffic will not work, so expect that ping
	commands will time out.

	The default device tree for sandbox includes an entry for lo on the sandbox
	host machine whose alias is "eth5". The following is an example of a network
	operation being tested on the lo interface.

	TFTP
	....

	set ethact eth5
	tftpboot u-boot.bin


	SPI Emulation
	-------------

	Sandbox supports SPI and SPI flash emulation.

	This is controlled by the spi_sf argument, the format of which is:

	bus:cs:device:file

	bus - SPI bus number
	cs - SPI chip select number
	device - SPI device emulation name
	file - File on disk containing the data

	For example:

	dd if=/dev/zero of=spi.bin bs=1M count=4
	./u-boot --spi_sf 0:0:M25P16:spi.bin

	With this setup you can issue SPI flash commands as normal:

	=>sf probe
	SF: Detected M25P16 with page size 64 KiB, total 2 MiB
	=>sf read 0 0 10000
	SF: 65536 bytes @ 0x0 Read: OK
	=>

	Since this is a full SPI emulation (rather than just flash), you can
	also use low-level SPI commands:

	=>sspi 0:0 32 9f
	FF202015

	This is issuing a READ_ID command and getting back 20 (ST Micro) part
	0x2015 (the M25P16).

	Drivers are connected to a particular bus/cs using sandbox's state
	structure (see the 'spi' member). A set of operations must be provided
	for each driver.


	Configuration settings for the curious are:

	CONFIG_SANDBOX_SPI_MAX_BUS
	The maximum number of SPI buses supported by the driver (default 1).

	CONFIG_SANDBOX_SPI_MAX_CS
	The maximum number of chip selects supported by the driver
	(default 10).

	CONFIG_SPI_IDLE_VAL
	The idle value on the SPI bus


	Block Device Emulation
	----------------------

	U-Boot can use raw disk images for block device emulation. To e.g. list
	the contents of the root directory on the second partion of the image
	"disk.raw", you can use the following commands:

	=>host bind 0 ./disk.raw
	=>ls host 0:2

	A disk image can be created using the following commands:

	$> truncate -s 1200M ./disk.raw
	$> echo -e "label: gpt\n,64M,U\n,,L" \| /usr/sbin/sgdisk ./disk.raw
	$> lodev=`sudo losetup -P -f --show ./disk.raw`
	$> sudo mkfs.vfat -n EFI -v ${lodev}p1
	$> sudo mkfs.ext4 -L ROOT -v ${lodev}p2

	or utilize the device described in test/py/make_test_disk.py:

	#!/usr/bin/python
	import make_test_disk
	make_test_disk.makeDisk()

	Writing Sandbox Drivers
	-----------------------

	Generally you should put your driver in a file containing the word 'sandbox'
	and put it in the same directory as other drivers of its type. You can then
	implement the same hooks as the other drivers.

	To access U-Boot's emulated memory, use map_sysmem() as mentioned above.

	If your driver needs to store configuration or state (such as SPI flash
	contents or emulated chip registers), you can use the device tree as
	described above. Define handlers for this with the SANDBOX_STATE_IO macro.
	See arch/sandbox/include/asm/state.h for documentation. In short you provide
	a node name, compatible string and functions to read and write the state.
	Since writing the state can expand the device tree, you may need to use
	state_setprop() which does this automatically and avoids running out of
	space. See existing code for examples.


	Testing
	-------

	U-Boot sandbox can be used to run various tests, mostly in the test/
	directory. These include:

	command_ut
	- Unit tests for command parsing and handling
	compression
	- Unit tests for U-Boot's compression algorithms, useful for
	security checking. It supports gzip, bzip2, lzma and lzo.
	driver model
	- Run this pytest
	./test/py/test.py --bd sandbox --build -k ut_dm -v
	image
	- Unit tests for images:
	test/image/test-imagetools.sh - multi-file images
	test/image/test-fit.py - FIT images
	tracing
	- test/trace/test-trace.sh tests the tracing system (see README.trace)
	verified boot
	- See test/vboot/vboot_test.sh for this

	If you change or enhance any of the above subsystems, you shold write or
	expand a test and include it with your patch series submission. Test
	coverage in U-Boot is limited, as we need to work to improve it.

	Note that many of these tests are implemented as commands which you can
	run natively on your board if desired (and enabled).

	It would be useful to have a central script to run all of these.

	--
	Simon Glass <sjg@chromium.org>
	Updated 22-Mar-14