Cartesi's reference off-chain implementation of Cartesi Machines is based on software emulation.
The emulator is written in C/C++ with POSIX dependencies restricted to the terminal, process, and memory-mapping facilities.
emulator/ directory in the Emulator SDK can be used to build and install the Cartesi Machine emulator.
It is written as a C++ library, but can be accessed in a variety of different ways.
When linked to a C++ application, the emulator can be controlled directly via the interface of the
C applications can control the emulator in a similar way, by means of a matching C API.
The emulator can also be accessed from the Lua programming language, via a
cartesi module that exposes a
cartesi.machine interface to Lua programs.
Additionally, Cartesi provides a gRPC server that can be run to control a Cartesi Machine instance remotely.
Finally, there is a command-line utility (written in Lua) that can configure and run Cartesi Machines for rapid prototyping.
The C, C++, Lua APIs as well as the command-line utility can seamlessly instantiate local emulators or connect to remote gRPC servers.
The documentation starts from the command-line utility,
This utility is used for most prototyping tasks.
The documentation then covers the Lua interface of
The C/C++/gRPC interfaces are very similar, and are covered only within their reference manuals.
Cartesi Machines are separated into a processor and a board. The processor performs the computations, executing the traditional fetch-execute loop while maintaining a variety of registers. The board defines the surrounding environment with an assortment of memories (ROM, RAM, flash drives) and a number of devices. Memories and devices are mapped to the 64-bit physical address space of the Cartesi Machine. The amount of RAM, as well as the number, length, and position of the flash drives in the address space can be chosen according to the needs of each particular application.
The initialization of a Cartesi Machine loads a ROM image, a RAM image, and a root file-system (as a flash drive) from regular files in the host file-system.
Execution starts from the ROM image, which contains a simple program that creates a description of the machine organization for the Linux kernel.
The ROM image
rom.bin can be built in the
rom/ directory in the Emulator SDK.
The Linux kernel itself resides in the RAM image
linux.bin, built in the
kernel/ directory in the Emulator SDK.
After it is done with its own initialization, the Linux kernel cedes control to the
/sbin/init program in the root file-system.
The root file-system
rootfs.ext2 contains all the data files and programs that make up an embedded Linux distribution.
It can be built in the
fs/ directory in the Emulator SDK.
The components of the target application can reside in the root file-system itself, or in their own, separate file-systems.
The emulator can be instructed to execute whatever command is necessary to start the target application.
For a complete description of the Cartesi Machine architecture and the boot process, see the documentation for the target perspective.
Two main types of target application are envisioned. In the first type, a Cartesi Machine is initialized and then run until the target application requests for the machine to halt. Additional flash drives can be used to provide inputs for the application, and to receive its outputs. (These can take the form entire file-systems or may contain raw data.) Once the machine halts, the outputs can be inspected by the host. This type of target application can be seen stateless, since nothing is implicitly carried over from one execution to the next.
The second type of target application runs in a loop that waits for a request carrying an input, performs any neccessary computations to service the request, and produces a suitable response. After processing a request, the target application asks the machine to yield control back to the host. The host inspects the response, prepares the input for the next request, and resumes the machine so the target application can perform the next iteration of the loop. This type of target application is statefull in the sense that whatever state changes happen during the processing of a request will remain in effect when the next request is processed.
The setup of a new development environment is often a time-consuming task.
This is particularly true in case of cross-development environments (i.e., when the development happens in a host platform but software runs in a different target platform).
With this in mind, the Cartesi team provides the
cartesi/playground Docker image, which enables immediate experimentation with Cartesi Machines.
This comes with a pre-built emulator and Lua interpreter accessible within the command-line, as well as a pre-built ROM image, RAM image, and root file-system.
It also comes with the cross-compiler for the RISC-V architecture on which the Cartesi Machine is based.
To enter the playground, open a terminal, download the Docker image from Cartesi's repository, and run it adequately mapping the current user and group information, as well as making the host's current directory available inside the container:
$ docker pull cartesi/playground:0.3.0$ docker run -it --rm -h playground \-e USER=$(id -u -n) \-e GROUP=$(id -g -n) \-e UID=$(id -u) \-e GID=$(id -g) \-v `pwd`:/home/$(id -u -n) \-w /home/$(id -u -n) \cartesi/playground:0.3.0 /bin/bash
Once inside, you can execute the
cartesi-machine utility as follows:
playground:~$ cartesi-machine --helpUsage:/opt/cartesi/bin/cartesi-machine.lua [options] [command] [arguments]where options are:--server-address=<address>Use a remote cartesi machine server listenning to <address> instead ofrunning a local cartesi machine.(requires --checkin-address)--checkin-address=<address>Address of the local checkin server to run.--server-shutdownShutdown the server after the execution.--ram-image=<filename>Name of file containing RAM image (default: "linux.bin").--no-ram-imageForget settings for RAM image.--ram-length=<number>Set RAM length.--rom-image=<filename>Name of file containing ROM image (default: "rom.bin").--no-rom-bootargsClear default bootargs.--append-rom-bootargs=<string>Append <string> to bootargs--no-root-flash-driveclear default root flash drive and associated bootargs parameters--flash-drive=<key>:<value>[,<key>:<value>[,...]...]defines a new flash drive, or modify an existing flash drive definitionflash drives appear as /dev/mtdblock[1-7]<key>:<value> is one oflabel:<label>filename:<filename>start:<number>length:<number>sharedlabel (mandatory)identifies the flash drive and init attempts to mount it as /mnt/<label>filename (optional)gives the name of the file containing the image for the flash drivewhen omitted or set to the empty string, the drive starts filled with 0start (optional)sets the starting physical memory offset for flash drive in byteswhen omitted, drives start at 2 << 63 and are spaced by 2 << 60if any start offset is set, all of them must be setlength (optional)gives the length of the flash drive in bytes (must be a multiple of 4Ki)if omitted, the length is computed from the image in filenameif length and filename are set, the image file size must match lengthshared (optional)target modifications to flash drive modify image file as wellby default, image files are not modified and changes are lost(an option "--flash-drive=label:root,filename:rootfs.ext2" is implicit)--replace-flash-drive=<key>:<value>[,<key>:<value>[,...]...]--replace-memory-range=<key>:<value>[,<key>:<value>[,...]...]replaces an existing flash drive or rollup memory range right aftermachine instantiation.(typically used in conjunction with the --load=<directory> option.)<key>:<value> is one offilename:<filename>start:<number>length:<number>sharedsemantics are the same as for the --flash-drive option with the followingdifference: start and length are mandatory, and must match those of apreviously existing flash drive or rollup memory memory range.--dhd=<key>:<value>[,<key>:<value>[,...]...]configures the dehashing deviceby default, the device is not present<key>:<value> is one offilename:<filename>tstart:<number>tlength:<number>filename (optional)gives the name of the file containing the initial dehashed data.when omitted or set to the empty string, the data starts filled with 0tstart (mandatory when device present)sets the start of target physical memory range for output datamust be aligned to tlengthtlength (mandatory when device present)gives the length of target physical memory range for output datamust be a power of 2 greater than 4Ki, or 0 when device not present--rollup-rx-buffer=<key>:<value>[,<key>:<value>[,...]...]--rollup-tx-buffer=<key>:<value>[,<key>:<value>[,...]...]--rollup-input-metadata=<key>:<value>[,<key>:<value>[,...]...]--rollup-voucher-hashes=<key>:<value>[,<key>:<value>[,...]...]--rollup-notice-hashes=<key>:<value>[,<key>:<value>[,...]...]defines the individual the memory ranges used by rollups<key>:<value> is one offilename:<filename>start:<number>length:<number>sharedsemantics are the same as for the --flash-drive option with the followingdifference: start and length are mandatory.--rollupdefines appropriate values for rollup-rx-buffer, rollup-tx-buffer,rollup-input-metadata, rollup-voucher-hashes, rollup-notice hashes,and htif yield for use with rollups.equivalent to the following options:--rollup-rx-buffer=start:0x60000000,length:2<<20--rollup-tx-buffer=start:0x60200000,length:2<<20--rollup-input-metadata=start:0x60400000,length:4096--rollup-voucher-hashes=start:0x60600000,length:2<<20--rollup-notice-hashes=start:0x60800000,length:2<<20--htif-yield-manual--htif-yield-automatic--rollup-advance-epoch=<key>:<value>[,<key>:<value>[,...]...]advances the state of the machine through an entire rollup epoch<key>:<value> is one ofepoch_index:<number>input:<filename-pattern>input_metadata:<filename-pattern>input_index_start:<number>input_index_end:<number>voucher:<filename-pattern>voucher_hashes: <filename>notice:<filename-pattern>notice_hashes: <filename>report:<filename-pattern>hashesepoch_indexthe index of the epochinput (default: "epoch-%e-input-%i.bin")the pattern that derives the name of the file read for input %iof epoch index %einput_index_start (default: 0)index of first input to advance (the first value of %i)input_index_end (default: 0)index of last input to advance (the last value of %i)input_metadata (default: "epoch-%e-input-metadata-%i.bin")the pattern that derives the name of the file read forinput metadata %i of epoch index %evoucher (default: "epoch-%e-input-%i-voucher-%o.bin")the pattern that derives the name of the file written for voucher %oof input %i of epoch %evoucher_hashes (default: "epoch-%e-input-%i-voucher-hashes.bin")the pattern that derives the name of the file written for the voucherhashes of input %i of epoch %enotice (default: "epoch-%e-input-%i-notice-%o.bin")the pattern that derives the name of the file written for notice %oof input %i of epoch %enotice_hashes (default: "epoch-%e-input-%i-notice-hashes.bin")the pattern that derives the name of the file written for the noticehashes of input %i of epoch %ereport (default: "epoch-%e-input-%i-report-%o.bin")the pattern that derives the name of the file written for report %oof input %i of epoch %ehashesprint out hashes before every input"%e" is replaced by the epoch index, "%i" by the input index and "%o" bythe voucher, notice, or report indexthe process starts with input--dhd-source=<address>server acting as source for dehashed data--concurrency=<key>:<value>[,<key>:<value>[,...]...]configures the number of threads used in some implementation parts.<key>:<value> is one ofupdate_merkle_tree:<number>update_merkle_tree (optional)defines the number of threads to use while calculating the merkle tree.when ommited or defined as 0, the number of hardware threads is used ifit can be identified or else a single thread is used.--max-mcycle=<number>stop at a given mcycle (default: 2305843009213693952)-i or --htif-console-getcharrun in interactive mode--htif-yield-manualhonor yield requests with manual reset by target--htif-yield-automatichonor yield requests with automatic reset by target--load=<directory>load prebuilt machine from <directory>--store=<directory>store machine to <directory>--initial-hashprint initial state hash before running machine--final-hashprint final state hash when done--periodic-hashes=<number-period>[,<number-start>]prints root hash every <number-period> cycles. If <number-start> is given,the periodic hashing will start at that mcycle. This option implies--initial-hash and --final-hash.(default: none)--stepprint step log for 1 additional cycle when done--json-steps=<filename>output json with step logs for all cycles to <filename>--store-config[=<filename>]store initial machine config to <filename>. If <filename> is omitted,print the initial machine config to stderr.--load-config=<filename>load initial machine config from <filename>. If a field is omitted onmachine_config table, it will fall back into the respective command-lineargument or into the default value.--dump-pmasdump all PMA ranges to disk when doneand command and arguments:commandthe full path to the program inside the target system(default: /bin/sh)argumentsthe given command arguments<number> can be specified in decimal (e.g., 16) or hexadeximal (e.g., 0x10),with a suffix multiplier (i.e., Ki, Mi, Gi for 2^10, 2^20, 2^30, respectively),or a left shift (e.g., 2 << 20).<address> is one of the following formats:<host>:<port>unix:<path><host> can be a host name, IPv4 or IPv6 address.
A final check can also be performed to verify if the contents inside the container are as expected:
playground:~$ md5sum /opt/cartesi/share/images/linux.bind1be2fa1a0dfd8b9ffae9be5ffbc506b /opt/cartesi/share/images/linux.binplayground:~$ md5sum /opt/cartesi/share/images/rom.bin670ca3cfb4618f30879e6c2f1f4eda7a /opt/cartesi/share/images/rom.binplayground:~$ md5sum /opt/cartesi/share/images/rootfs.ext210afa1ee46365bf01f9d7c9384c42997 /opt/cartesi/share/images/rootfs.ext2