Re: [Qemu-devel] [RESEND][PATCH] gdbstub: Add vCont support

[Anthony Liguori <anthony@codemonkey.ws>]

Jan Kiszka wrote:
> [ Also available via git://git.kiszka.org/qemu.git queue/gdb ]
>
> In order to set the VCPU for the next single-step command, you need gdb
> 6.8 or better - and this patch. It enhances the existing support for
> representing VCPUs as threads to the gdb frontend by introducing the
> vCont remote gdb command. This is used by gdb to switch the debugging
> focus for single-stepping multi-threaded targets.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>   

I think the consensus from the last posting of this was that modeling 
threads was pretty broken and that we should model as processes.  Did I 
miss something there?

Regards,

Anthony Liguori

> ---
>
>  gdbstub.c |   56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 56 insertions(+), 0 deletions(-)
>
> diff --git a/gdbstub.c b/gdbstub.c
> index 0bcd5d5..1cb20b7 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -1542,6 +1542,62 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
>              s->signal = 0;
>          gdb_continue(s);
>          return RS_IDLE;
> +    case 'v':
> +        if (strncmp(p, "Cont", 4) == 0) {
> +            int res_signal, res_thread;
> +
> +            p += 4;
> +            if (*p == '?') {
> +                put_packet(s, "vCont;c;C;s;S");
> +                break;
> +            }
> +            res = 0;
> +            res_signal = 0;
> +            res_thread = 0;
> +            while (*p) {
> +                int action, signal;
> +
> +                if (*p++ != ';') {
> +                    res = 0;
> +                    break;
> +                }
> +                action = *p++;
> +                signal = 0;
> +                if (action == 'C' || action == 'S')
> +                    signal = strtoul(p, (char **)&p, 16);
> +                else if (action != 'c' && action != 's') {
> +                    res = 0;
> +                    break;
> +                }
> +                thread = 0;
> +                if (*p == ':')
> +                    thread = strtoull(p+1, (char **)&p, 16);
> +
> +                action = tolower(action);
> +                if (res == 0 || (res == 'c' && action == 's')) {
> +                    res = action;
> +                    res_signal = signal;
> +                    res_thread = thread;
> +                }
> +            }
> +            if (res) {
> +                if (res_thread != -1 && res_thread != 0) {
> +                    for (env = first_cpu; env != NULL; env = env->next_cpu)
> +                        if (env->cpu_index + 1 == res_thread)
> +                            break;
> +                    if (env == NULL) {
> +                        put_packet(s, "E22");
> +                        break;
> +                    }
> +                    s->c_cpu = env;
> +                }
> +                if (res == 's')
> +                    cpu_single_step(s->c_cpu, sstep_flags);
> +                gdb_continue(s);
> +                return RS_IDLE;
> +            }
> +            break;
> +        }
>      case 'k':
>          /* Kill the target */
>          fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
>
>
>