Re: [Qemu-devel] [PATCH] target-i386: Improve x86_cpu_list output

[Igor Mammedov]

On Wed, 27 Feb 2013 00:26:38 -0300
Eduardo Habkost <address@hidden> wrote:

> On Tue, Feb 26, 2013 at 10:57:56PM +0100, Igor Mammedov wrote:
> > On Sat, 23 Feb 2013 16:45:00 +0100
> > Jan Kiszka <address@hidden> wrote:
> > 
> > > From: Jan Kiszka <address@hidden>
> > > 
> > > Several issues fixed:
> > >  - We were missing a bunch of feature lists. Fix this by simply dumping
> > >    the meta list feature_word_info.
> > >  - kvm_enabled() cannot be true at this point because accelerators are
> > >    initialized much later during init. Simply dump unconditionally.
> > Why not to move list_cpu after accelerators are initialized?
> 
> Because help output is simply documentation and shouldn't depend on any
> other config option parsing or accelerator initialization at all?
Don't see reason why it shouldn't.
It's not a man page but a program and can do pretty much everything.

> 
> > 
> > >  - Add explanation for "host" CPU type.
> > > 
> > > Signed-off-by: Jan Kiszka <address@hidden>
> > > ---
> > >  target-i386/cpu.c |   20 +++++++++-----------
> > >  1 files changed, 9 insertions(+), 11 deletions(-)
> > > 
> > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > > index dfcf86e..6e742f0 100644
> > > --- a/target-i386/cpu.c
> > > +++ b/target-i386/cpu.c
> > > @@ -1453,18 +1453,16 @@ void x86_cpu_list(FILE *f, fprintf_function 
> > > cpu_fprintf)
> > >          snprintf(buf, sizeof(buf), "%s", def->name);
> > >          (*cpu_fprintf)(f, "x86 %16s  %-48s\n", buf, def->model_id);
> > >      }
> > > -    if (kvm_enabled()) {
> > > -        (*cpu_fprintf)(f, "x86 %16s\n", "[host]");
> > > -    }
> > > +    (*cpu_fprintf)(f, "x86 %16s  %-48s\n", "host",
> > > +                   "KVM processor with all supported host features");
> > > +
> > that would make 'host' visible to users even if QEMU compiled without KVM
> > support. No big harm, but autotest could get confused when it gets 'host' 
> > CPU
> > but QEMU doesn't run because it's not really supported.
> 
> Then we have to fix the autotest test code to not try it without KVM.
> :-)
> 
> Help output is not a probing mechanism (although we often misuse it as
> if it were), and I expect help output to be static and not depend on any
> subsystem initialization.
Then fix help output and add to "host" line something like " is available with
-enable-kvm on command line and if your build was compiled --enable-kvm
configure option", otherwise 'host' is misleading.
Now even without 'host' in output of -cpu 'help', question why 'host' is not
found periodically pops up on IRC. This change will just increase frequency of
it.

> 
> For example: an user without permission to open /dev/kvm should be still
> able to see help text explaining that "-cpu host" is available when KVM
> is enabled and working.
which is not correct, since it isn't available.

> 
> 
> > 
> > >      (*cpu_fprintf)(f, "\nRecognized CPUID flags:\n");
> > > -    listflags(buf, sizeof(buf), (uint32_t)~0, feature_name, 1);
> > > -    (*cpu_fprintf)(f, "  %s\n", buf);
> > > -    listflags(buf, sizeof(buf), (uint32_t)~0, ext_feature_name, 1);
> > > -    (*cpu_fprintf)(f, "  %s\n", buf);
> > > -    listflags(buf, sizeof(buf), (uint32_t)~0, ext2_feature_name, 1);
> > > -    (*cpu_fprintf)(f, "  %s\n", buf);
> > > -    listflags(buf, sizeof(buf), (uint32_t)~0, ext3_feature_name, 1);
> > > -    (*cpu_fprintf)(f, "  %s\n", buf);
> > > +    for (i = 0; i < ARRAY_SIZE(feature_word_info); i++) {
> > > +        FeatureWordInfo *fw = &feature_word_info[i];
> > > +
> > > +        listflags(buf, sizeof(buf), (uint32_t)~0, fw->feat_names, 1);
> > > +        (*cpu_fprintf)(f, "  %s\n", buf);
> > > +    }
> > >  }
> > >  
> > >  CpuDefinitionInfoList *arch_query_cpu_definitions(Error **errp)
> > > -- 
> > > 1.7.3.4
> > > 
> > 
> > 
> > -- 
> > Regards,
> >   Igor
> 
> -- 
> Eduardo


-- 
Regards,
  Igor