Re: [Qemu-devel] [PATCH 2/2] target-i386: use visit_type_unit_suffixed_int() to parse tsc_freq property value

[mdroth <mdroth@linux.vnet.ibm.com>]

On Mon, Dec 10, 2012 at 05:13:45PM +0100, Igor Mammedov wrote:
> On Fri, 7 Dec 2012 18:09:06 -0200
> Eduardo Habkost <ehabkost@redhat.com> wrote:
> 
> > On Fri, Dec 07, 2012 at 08:00:09PM +0100, Andreas Färber wrote:
> > > Am 06.12.2012 22:12, schrieb Igor Mammedov:
> > > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > > > ---
> > > >   v2:
> > > >    - replace visit_type_freq() with visit_type_unit_suffixed_int()
> > > >      in x86_cpuid_set_tsc_freq()
> > > > ---
> > > >  target-i386/cpu.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > > > index c6c2ca0..b7f0aba 100644
> > > > --- a/target-i386/cpu.c
> > > > +++ b/target-i386/cpu.c
> > > > @@ -1195,7 +1195,7 @@ static void x86_cpuid_set_tsc_freq(Object *obj,
> > > > Visitor *v, void *opaque, const int64_t max = INT64_MAX;
> > > >      int64_t value;
> > > >  
> > > > -    visit_type_int(v, &value, name, errp);
> > > > +    visit_type_unit_suffixed_int(v, &value, name, 1000, errp);
> > > >      if (error_is_set(errp)) {
> > > >          return;
> > > >      }
> > > 
> > > This trivial usage is fine obviously. But since this series set out to
> > > make things more generic I am missing at least one use case for 1024.
> > > Does nothing like that exist in qdev-properties.c or so already?
> > 
> > cutils.c has:
> > 
> > int64_t strtosz_suffix(const char *nptr, char **end, const char
> > default_suffix) {
> >     return strtosz_suffix_unit(nptr, end, default_suffix, 1024);
> > }
> > 
> > $ git grep -w strtosz_suffix
> > [...]
> > qapi/opts-visitor.c:    val = strtosz_suffix(opt->str ? opt->str : "",
> > &endptr, qemu-img.c:        sval = strtosz_suffix(argv[optind++], &end,
> > STRTOSZ_DEFSUFFIX_B); qemu-img.c:            sval = strtosz_suffix(optarg,
> > &end, STRTOSZ_DEFSUFFIX_B);
> > 
> > The opts-visitor.c match, in turn, is inside opts_type_size(), that's the
> > ->type_size method of OptsVisitor. There are many 'size' elements inside
> > qapi-schema.json.
> > 
> > I don't see any code using visit_type_size() directly, but I see two users
> > of type 'size' on qapi-schema.json: NetdevTapOptions and NetdevDumpOptions.
> > 
> > I didn't know that we already had a visitor method using the suffixed-int
> > parsing code. Should we change the visit_type_size() code to be to use use
> > the new generic ->type_suffixed_int method and kill ->type_size?
> 
> If there isn't strong opposition to do it in incremental way,
> I'd prefer for these patches go in first.
> 
> And then later fix users of visit_type_size() to use type_suffixed_int() or
> maybe have a new type_suffixed_uint() so that size could be represented as
> uint64_t instead of int64_t as it's now. That would require to
> rewrite strtosz_* and its callers a bit.

I think that seems reasonable. Between the 2 that should give us a nice
way to support [KMGx] suffixes for options in a backward-compatible way.

Shame that users don't have a well-established way to specify base 2 vs.
10, but so long as we document our choice for each option that should
cover most cases well enough.