Debugging Baremetal Applications Using nSIM

Building and Debugging Applications

nSIM supports running and debugging applications for all ARC families. Debugging is not supported for ARCv3 families yet.

Building and Running "Hello, World!"

Consider a simple example code (save it as main.c):

#include <stdio.h>

int main()
{
    printf("Hello, World!\n");
    return 0;
}

You need to use -specs=nsim.specs to use input/output features and to pass -on nsim_emt option to nSIM to use ARC GNU input/output protocol:

$ arc-elf32-gcc -mcpu=archs -specs=nsim.specs main.c -o main.elf
$ nsimdrv -tcf $NSIM_HOME/etc/tcf/templates/hs38_full.tcf -on nsim_emt main.elf
Hello, World!

You can use MetaWare's own hostlink protocol for input/output operations by passing -specs=hl.specs to GCC. In this case you don't have to pass any additional options to nSIM:

$ arc-elf32-gcc -mcpu=archs -specs=hl.specs main.c -o main.elf
$ nsimdrv -tcf $NSIM_HOME/etc/tcf/templates/hs38_full.tcf main.elf
Hello, World!

Using nCAM Model and Profiling

You can run nSIM in NCAM mode - Near Cycle-Accurate Mode. This mode activates counters that depend on micro-architectural simulations. It may be a good tool for optimization and exploration. NCAM's model is not cycle-accurate and it's not derived from RTL, but it's much faster than xCAM. If you need a cycle-accurate model then consider using xCAM models.

Use -on cycles to enable NCAM:

$ nsimdrv -on cycles main.elf

Print simulation statistics at the end of a simulation using -on nsim_print_stats_on_exit option:

$ nsimdrv -on nsim_print_stats_on_exit main.elf

Use -on nsim_trace and -p nsim_trace-output=trace.txt options to trace instructions (omit nsim_trace-output if you want to print trace log right into stdout):

$ nsimdrv -on nsim_trace -p nsim_trace-output=trace.txt main.elf
$ head trace.txt

                nSIM, Version: 2023.03 (Build: 002)

[0x00000124] 0x226a0280                 K       lr             r2,[0xa] : (w0) r2 <= 0x00000000: aux[0x0a] => 0x00 *
[0x00000128] 0x224f04c2                 K       bset           r2,r2,0x13 : (w0) r2 <= 0x00080000 *
[0x0000012c] 0x20290080                 K       flag           r2 *
[0x00000130] 0x26ab740a 0x00000122   AD K       sr             00000122,0x290: aux[0x290] <= 0x122 *
[0x00000138] 0x220a3f80 0x00005c10   AD K       mov            gp,00005c10 : (w0) r26 <= 0x00005c10 *
[0x00000140] 0x42c3     0x00005b20   AD K       mov_s          r2,00005b20 : (w0) r2 <= 0x00005b20 *
[0x00000146] 0x26027083 0x00005e34   AD K       sub            r3,00005e34,r2 : (w0) r3 <= 0x00000314 *