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Re: [libvirt] [PATCH 8/9] target-i386: Use "-" instead of "_" on all feature names



On Tue, May 24, 2016 at 03:22:27PM +0200, Igor Mammedov wrote:
> On Tue, 24 May 2016 09:34:05 -0300
> Eduardo Habkost <ehabkost redhat com> wrote:
> 
> > On Tue, May 24, 2016 at 02:17:03PM +0200, Igor Mammedov wrote:
> > > On Fri,  6 May 2016 15:11:31 -0300
> > > Eduardo Habkost <ehabkost redhat com> wrote:
[...]
> > > > -/* Convert all '_' in a feature string option name to '-', to make feature
> > > > - * name conform to QOM property naming rule, which uses '-' instead of '_'.
> > > > +/* Convert all '_' in a feature string option name to '-', to keep compatibility
> > > > + * with old feature names that used "_" instead of "-".
> > > >   */
> > > >  static inline void feat2prop(char *s)
> > > >  {
> > > > @@ -1925,8 +1925,10 @@ static void x86_cpu_parse_featurestr(CPUState *cs, char *features,
> > > >      while (featurestr) {
> > > >          char *val;  
> > > I'd place a single feat2prop() here
> > > and delete it from other call sites in this function.  
> > 
> > A previous version of this patch had it. But it would change the
> > property value too, not just the property name (breaking stuff
> > like "model-id=some_string").
> >
> it's bug in feat2prop(), which probably should be fixed there,
> so it would do what comment above it says. Or as alternative:

The comment above it doesn't say anything about stopping at a '='
delimiter. I always expected it to just replace "_" with "-" in a
null-terminated string.

(I am not completely against making it stop at '=', but I believe
your suggestion below sounds better).

> 
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index ca2a893..e46e4c3 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1941,14 +1941,16 @@ static void x86_cpu_parse_featurestr(CPUState *cs, char *features
>      featurestr = features ? strtok(features, ",") : NULL;
>  
>      while (featurestr) {
> -        char *val;
> +        char *val = strchr(featurestr, '=');
> +        if (val) {
> +            *val = 0; val++;
> +        }
> +        feat2prop(featurestr);

This would make "+feature=FOO" treated as a valid option, and it
isn't. It would keep the existing behavior if we did this:

-          if (featurestr[0] == '+') {
+          if (featurestr[0] == '+' && !val) {
               add_flagname_to_bitmaps(featurestr + 1, plus_features, &local_err);
-          } else if (featurestr[0] == '-') {
+          if (featurestr[0] == '+' && !val) {
               add_flagname_to_bitmaps(featurestr + 1, minus_features, &local_err);

In either case, I prefer to get this optimization reviewed as a
separate patch. Can you send it as a follow-up?

> -        } else if ((val = strchr(featurestr, '='))) {
> -            *val = 0; val++;
> -            feat2prop(featurestr);
> +        } else if (val) {
>              if (!strcmp(featurestr, "xlevel")) {
>                  char *err;
>                  char num[32];
> @@ -2000,7 +2002,6 @@ static void x86_cpu_parse_featurestr(CPUState *cs, char *features,
>                  object_property_parse(OBJECT(cpu), val, featurestr, &local_err);
>              }
>          } else {
> -            feat2prop(featurestr);
>              object_property_parse(OBJECT(cpu), "on", featurestr, &local_err);
>          }
>          if (local_err) {
> 
> 

-- 
Eduardo


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