diff --git a/README.md b/README.md index 83d4503e..0639d727 100644 --- a/README.md +++ b/README.md @@ -218,12 +218,12 @@ 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: +tries to be like real hardware, you also need OpenOCD to do that. +We'll use the following test program: + ``` -$ cat rot13.c +$ cat rot13.c +#include char text[] = "Vafgehpgvba frgf jnag gb or serr!"; // Don't use the stack, because sp isn't set up. @@ -231,10 +231,6 @@ 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; @@ -244,28 +240,17 @@ int main() text[i] -= 13; i++; } - done: - while (!wait) - ; -} -$ cat spike.lds -OUTPUT_ARCH( "riscv" ) - -SECTIONS -{ - . = 0x10110000; - .text : { *(.text) } - .data : { *(.data) } + printf("decoded text: %s\n", text); } -$ 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 +$ riscv64-unknown-elf-gcc -g -Og --specs=semihost.specs -o rot13 rot13.c ``` To debug this program, first run spike telling it to listen for OpenOCD: ``` -$ spike --rbb-port=9824 -m0x10100000:0x20000 rot13-64 +$ spike --rbb-port=9824 -m0x10000:0x20000 rot13 Listening for remote bitbang connection on port 9824. +... ``` In a separate shell run OpenOCD with the appropriate configuration file: @@ -281,54 +266,59 @@ 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 +gdb report_data_abort enable init +arm semihosting enable halt $ openocd -f spike.cfg -Open On-Chip Debugger 0.10.0-dev-00002-gc3b344d (2017-06-08-12:14) +Open On-Chip Debugger 0.12.0 +... +Info : starting gdb server for riscv.cpu on 3333 +Info : Listening on port 3333 for gdb connections +riscv.cpu halted due to debug-request. Semihosting is active. ... 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 -$3 = "Vafgehpgvba frgf jnag gb or serr!" -(gdb) b done -Breakpoint 1 at 0x10110064: file rot13.c, line 22. +$ riscv64-unknown-elf-gdb rot13 +... +Reading symbols from rot13... +(gdb) target extended-remote localhost:3333 +... +(gdb) load +... +(gdb) set $sp=0x2fff0 +(gdb) b main +Breakpoint 1 at 0x10202: file rot13.c, line 5. (gdb) c Continuing. Disabling abstract command writes to CSRs. -Breakpoint 1, main () at rot13.c:23 -23 while (!wait) -(gdb) print wait -$4 = 0 +Breakpoint 1, main () at rot13.c:5 +5 { (gdb) print text +$1 = "Vafgehpgvba frgf jnag gb or serr!" +(gdb) until done +[riscv.cpu] Found 4 triggers +main () at rot13.c:16 +16 printf("decoded text: %s\n", text); +(gdb) c +Continuing. + +Program received signal SIGTRAP, Trace/breakpoint trap. +0x00019ff8 in _exit () +(gdb) +... +``` + +On the OpenOCD terminal you will have: + +``` ... +decoded text: Instruction sets want to be free! +semihosting: *** application exited with 0 *** +riscv.cpu halted due to breakpoint. Semihosting is active. ```