Re: [PULL 10/11] trace: document how to specify multiple --trace patterns

[Paolo Bonzini]

On 02/02/21 13:41, Markus Armbruster wrote:
> Since trace_opt_parse() deletes, this always creates an empty one.
>
>          const char *file = qemu_opt_get(opts, "file");
>
> This is always null.
>
>      #ifdef CONFIG_TRACE_SIMPLE
>          st_set_trace_file(file);
>          if (init_trace_on_startup) {
>              st_set_trace_file_enabled(true);
>          }
>      #elif defined CONFIG_TRACE_LOG
>          /*
>           * If both the simple and the log backends are enabled, "--trace file"
>           * only applies to the simple backend; use "-D" for the log
>           * backend. However we should only override -D if we actually have
>           * something to override it with.
>           */
>          if (file) {
>              qemu_set_log_filename(file, &error_fatal);
>          }
>      #else
>          if (file) {
>              fprintf(stderr, "error: --trace file=...: "
>                      "option not supported by the selected tracing backends\n");
>              exit(1);
>          }
>      #endif
>      }
>
> Bug: option parameter "file" has no effect.  I suspect this was broken
> in commit 92eecfff32 "trace: remove argument from trace_init_file",
> 2020-11-11.

Indeed, and I'll fix it.

Paolo