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https://github.com/riscv-software-src/riscv-isa-sim

Spike, a RISC-V ISA Simulator
https://github.com/riscv-software-src/riscv-isa-sim

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Spike, a RISC-V ISA Simulator

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README 

        
Spike RISC-V ISA Simulator

============================



About

-------------



Spike, the RISC-V ISA Simulator, implements a functional model of one or more

RISC-V harts.  It is named after the golden spike used to celebrate the

completion of the US transcontinental railway.



Spike supports the following RISC-V ISA features:

  - RV32I and RV64I base ISAs, v2.1

  - RV32E and RV64E base ISAs, v1.9

  - Zifencei extension, v2.0

  - Zicsr extension, v2.0

  - Zicntr extension, v2.0

  - M extension, v2.0

  - A extension, v2.1

  - B extension, v1.0

  - F extension, v2.2

  - D extension, v2.2

  - Q extension, v2.2

  - C extension, v2.0

  - Zbkb, Zbkc, Zbkx, Zknd, Zkne, Zknh, Zksed, Zksh scalar cryptography extensions (Zk, Zkn, and Zks groups), v1.0

  - Zkr virtual entropy source emulation, v1.0

  - V extension, v1.0 (_requires a 64-bit host_)

  - P extension, v0.9.2

  - Zba extension, v1.0

  - Zbb extension, v1.0

  - Zbc extension, v1.0

  - Zbs extension, v1.0

  - Zfh and Zfhmin half-precision floating-point extensions, v1.0

  - Zfinx extension, v1.0

  - Zmmul integer multiplication extension, v1.0

  - Zicbom, Zicbop, Zicboz cache-block maintenance extensions, v1.0

  - Conformance to both RVWMO and RVTSO (Spike is sequentially consistent)

  - Machine, Supervisor, and User modes, v1.11

  - Hypervisor extension, v1.0

  - Svnapot extension, v1.0

  - Svpbmt extension, v1.0

  - Svinval extension, v1.0

  - Svadu extension, v1.0

  - Sdext extension, v1.0-STABLE

  - Sdtrig extension, v1.0-STABLE

  - Smepmp extension v1.0

  - Smstateen extension, v1.0

  - Smdbltrp extension, v1.0

  - Sscofpmf v0.5.2

  - Ssdbltrp extension, v1.0

  - Ssqosid extension, v1.0

  - Zaamo extension, v1.0

  - Zalrsc extension, v1.0

  - Zabha extension, v1.0

  - Zacas extension, v1.0

  - Zawrs extension, v1.0

  - Zicfiss extension, v1.0

  - Zicfilp extension, v1.0

  - Zca extension, v1.0

  - Zcb extension, v1.0

  - Zcf extension, v1.0

  - Zcd extension, v1.0

  - Zcmp extension, v1.0

  - Zcmt extension, v1.0

  - Zfbfmin extension, v0.6

  - Zvfbfmin extension, v0.6

  - Zvfbfwma extension, v0.6

  - Zvbb extension, v1.0

  - Zvbc extension, v1.0

  - Zvkg extension, v1.0

  - Zvkned extension, v1.0

  - Zvknha, Zvknhb extension, v1.0

  - Zvksed extension, v1.0

  - Zvksh extension, v1.0

  - Zvkt  extension, v1.0

  - Zvkn, Zvknc, Zvkng extension, v1.0

  - Zvks, Zvksc, Zvksg extension, v1.0 

  - Zicond extension, v1.0

  - Zilsd extension, v0.10

  - Zclsd extension, v0.10



Versioning and APIs

-------------------



Projects are versioned primarily to indicate when the API has been extended or

rendered incompatible.  In that spirit, Spike aims to follow the

[SemVer](https://semver.org/spec/v2.0.0.html) versioning scheme, in which

major version numbers are incremented when backwards-incompatible API changes

are made; minor version numbers are incremented when new APIs are added; and

patch version numbers are incremented when bugs are fixed in

a backwards-compatible manner.



Spike's principal public API is the RISC-V ISA.  _The C++ interface to Spike's

internals is **not** considered a public API at this time_, and

backwards-incompatible changes to this interface _will_ be made without

incrementing the major version number.



Build Steps

---------------



We assume that the RISCV environment variable is set to the RISC-V tools

install path.



    $ apt-get install device-tree-compiler libboost-regex-dev libboost-system-dev

    $ mkdir build

    $ cd build

    $ ../configure --prefix=$RISCV

    $ make

    $ [sudo] make install



If your system uses the `yum` package manager, you can substitute

`yum install dtc` for the first step.



Build Steps on OpenBSD

----------------------



Install bash, gmake, dtc, and use clang.



    $ pkg_add bash gmake dtc

    $ exec bash

    $ export CC=cc; export CXX=c++

    $ mkdir build

    $ cd build

    $ ../configure --prefix=$RISCV

    $ gmake

    $ [doas] make install



Compiling and Running a Simple C Program

-------------------------------------------



Install spike (see Build Steps), riscv-gnu-toolchain, and riscv-pk.



Write a short C program and name it hello.c.  Then, compile it into a RISC-V

ELF binary named hello:



    $ riscv64-unknown-elf-gcc -o hello hello.c



Now you can simulate the program atop the proxy kernel:



    $ spike pk hello



Simulating a New Instruction

------------------------------------



Adding an instruction to the simulator requires two steps:



  1.  Describe the instruction's functional behavior in the file

      riscv/insns/.h.  Examine other instructions

      in that directory as a starting point.



  2.  Add the opcode and opcode mask to riscv/opcodes.h.  Alternatively,

      add it to the riscv-opcodes package, and it will do so for you:

        ```

         $ cd ../riscv-opcodes

         $ vi opcodes       // add a line for the new instruction

         $ make install

        ```



  3.  Add the instruction to riscv/riscv.mk.in. Otherwise, the instruction

      will not be included in the build and will be treated as an illegal instruction.



  4.  Rebuild the simulator.



Interactive Debug Mode

---------------------------



To invoke interactive debug mode, launch spike with -d:



    $ spike -d pk hello



To see the contents of an integer register (0 is for core 0):



    : reg 0 a0



To see the contents of a floating point register:



    : fregs 0 ft0



or:



    : fregd 0 ft0



depending upon whether you wish to print the register as single- or double-precision.



To see the contents of a memory location (physical address in hex):



    : mem 2020



To see the contents of memory with a virtual address (0 for core 0):



    : mem 0 2020



You can advance by one instruction by pressing the enter key. You can also

execute until a desired equality is reached:



    : until pc 0 2020                   (stop when pc=2020)

    : until reg 0 mie a                 (stop when register mie=0xa)

    : until mem 2020 50a9907311096993   (stop when mem[2020]=50a9907311096993)



Alternatively, you can execute as long as an equality is true:



    : while mem 2020 50a9907311096993



You can continue execution indefinitely by:



    : r



At any point during execution (even without -d), you can enter the

interactive debug mode with `-`.



To end the simulation from the debug prompt, press `-` or:



    : q



Debugging With Gdb

------------------



An alternative to interactive debug mode is to attach using gdb. Because spike

tries to be like real hardware, you also need OpenOCD to do that. OpenOCD

doesn't currently know about address translation, so it's not possible to

easily debug programs that are run under `pk`. We'll use the following test

program:

```

$ cat rot13.c 

char text[] = "Vafgehpgvba frgf jnag gb or serr!";



// Don't use the stack, because sp isn't set up.

volatile int wait = 1;



int main()

{

    while (wait)

        ;



    // Doesn't actually go on the stack, because there are lots of GPRs.

    int i = 0;

    while (text[i]) {

        char lower = text[i] | 32;

        if (lower >= 'a' && lower <= 'm')

            text[i] += 13;

        else if (lower > 'm' && lower <= 'z')

            text[i] -= 13;

        i++;

    }



done:

    while (!wait)

        ;

}

$ cat spike.lds 

OUTPUT_ARCH( "riscv" )



SECTIONS

{

  . = 0x10110000;

  .text : { *(.text) }

  .data : { *(.data) }

}

$ riscv64-unknown-elf-gcc -g -Og -o rot13-64.o -c rot13.c

$ riscv64-unknown-elf-gcc -g -Og -T spike.lds -nostartfiles -o rot13-64 rot13-64.o

```



To debug this program, first run spike telling it to listen for OpenOCD:

```

$ spike --rbb-port=9824 -m0x10100000:0x20000 rot13-64

Listening for remote bitbang connection on port 9824.

```



In a separate shell run OpenOCD with the appropriate configuration file:

```

$ cat spike.cfg 

adapter driver remote_bitbang

remote_bitbang host localhost

remote_bitbang port 9824



set _CHIPNAME riscv

jtag newtap $_CHIPNAME cpu -irlen 5 -expected-id 0xdeadbeef



set _TARGETNAME $_CHIPNAME.cpu

target create $_TARGETNAME riscv -chain-position $_TARGETNAME



gdb_report_data_abort enable



init

halt

$ openocd -f spike.cfg

Open On-Chip Debugger 0.10.0-dev-00002-gc3b344d (2017-06-08-12:14)

...

riscv.cpu: target state: halted

```



In yet another shell, start your gdb debug session:

```

tnewsome@compy-vm:~/SiFive/spike-test$ riscv64-unknown-elf-gdb rot13-64

GNU gdb (GDB) 8.0.50.20170724-git

Copyright (C) 2017 Free Software Foundation, Inc.

License GPLv3+: GNU GPL version 3 or later 

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.  Type "show copying"

and "show warranty" for details.

This GDB was configured as "--host=x86_64-pc-linux-gnu --target=riscv64-unknown-elf".

Type "show configuration" for configuration details.

For bug reporting instructions, please see:

.

Find the GDB manual and other documentation resources online at:

.

For help, type "help".

Type "apropos word" to search for commands related to "word"...

Reading symbols from rot13-64...done.

(gdb) target remote localhost:3333

Remote debugging using localhost:3333

0x0000000010010004 in main () at rot13.c:8

8	    while (wait)

(gdb) print wait

$1 = 1

(gdb) print wait=0

$2 = 0

(gdb) print text

$3 = "Vafgehpgvba frgf jnag gb or serr!"

(gdb) b done 

Breakpoint 1 at 0x10110064: file rot13.c, line 22.

(gdb) c

Continuing.

Disabling abstract command writes to CSRs.



Breakpoint 1, main () at rot13.c:23

23	    while (!wait)

(gdb) print wait

$4 = 0

(gdb) print text

...

```