[Qemu-devel] Re: [PATCH] flush TB on singlestep command

[Jan Kiszka <jan.kiszka@web.de>]

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Jun Koi wrote:
> Thank you for the explanation of this code.
> 
> Qemu has a command named singlestep, which reduces the translated code
> block to be only one instruction.
> This new patch flushes TBs both when singlestep is on and off.
> 
> Signed-off-by: Jun Koi <junkoi2004@gmail.com>
> 
> 
> diff --git a/monitor.c b/monitor.c
> index 5659991..2b2005b 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -1187,13 +1187,26 @@ static void do_log(Monitor *mon, const QDict *qdict)
>      cpu_set_log(mask);
>  }
> 
> +/* flush all the TBs to force new code generation */
> +static void flush_all_tb(void)
> +{
> +    CPUState *env;
> +
> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
> +        tb_flush(env);
> +    }
> +}
> +

The smaller your patch are, the more people pick on it. :)

I was about to suggest moving this close to tb_flush, but then I
realized that the env argument of that service is misleading. In fact,
it already flushes the one and only translation buffer pool.

>  static void do_singlestep(Monitor *mon, const QDict *qdict)
>  {
>      const char *option = qdict_get_try_str(qdict, "option");
> +
>      if (!option || !strcmp(option, "on")) {
>          singlestep = 1;
> +        flush_all_tb();
>      } else if (!strcmp(option, "off")) {
>          singlestep = 0;
> +        flush_all_tb();
>      } else {
>          monitor_printf(mon, "unexpected option %s\n", option);
>      }
> 

Let's just pass mon->mon_cpu to tb_flush and skip the redundant loop.

Jan


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