KDB_TRACE and no backend

[Attilio Rao]

2010/9/18 Andriy Gapon <avg at icyb.net.ua>:
>
> Here's a small patch that adds support for printing stack trace in form of frame
> addresses when KDB_TRACE is enabled, but there is no debugger backend configured.
> The patch is styled after "cheap" variant of stack_ktr.
>
> What do you think (useful/useless, correct, etc) ?
>
> --- a/sys/kern/subr_kdb.c
> +++ b/sys/kern/subr_kdb.c
> @@ -37,6 +37,7 @@
>  #include <sys/pcpu.h>
>  #include <sys/proc.h>
>  #include <sys/smp.h>
> +#include <sys/stack.h>
>  #include <sys/sysctl.h>
>
>  #include <machine/kdb.h>
> @@ -295,10 +296,16 @@
>  void
>  kdb_backtrace(void)
>  {
> +       struct stack st;
> +       int i;
>
> -       if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
> -               printf("KDB: stack backtrace:\n");
> +       printf("KDB: stack backtrace:\n");
> +       if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL)
>                kdb_dbbe->dbbe_trace();
> +       else {
> +               stack_save(&st);
> +               for (i = 0; i < st.depth; i++)
> +                       printf("#%d %p\n", i, (void*)(uintptr_t)st.pcs[i]);
>        }
>  }

You have to eventually wrap this logic within the 'STACK' option
(opt_stack.h for the check) because stack_save() will be uneffective
otherwise. STACK should be mandatory for DDB I guess, but it is not
for KDB.

Thanks,
Attilio


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