Re: [PATCH 3/5] target/i386: convert to use format_state instead of dump_state

[Daniel P . Berrangé]

On Wed, Sep 08, 2021 at 01:05:13PM -0500, Eric Blake wrote:
> On Wed, Sep 08, 2021 at 11:37:09AM +0100, Daniel P. Berrangé wrote:
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> >  target/i386/cpu-dump.c | 325 ++++++++++++++++++++++-------------------
> >  target/i386/cpu.c      |   2 +-
> >  target/i386/cpu.h      |   2 +-
> >  3 files changed, 174 insertions(+), 155 deletions(-)
> > 
> > diff --git a/target/i386/cpu-dump.c b/target/i386/cpu-dump.c
> > index 02b635a52c..8e19485a20 100644
> > --- a/target/i386/cpu-dump.c
> > +++ b/target/i386/cpu-dump.c
> > @@ -94,41 +94,45 @@ static const char *cc_op_str[CC_OP_NB] = {
> >  };
> >  
> >  static void
> > -cpu_x86_dump_seg_cache(CPUX86State *env, FILE *f,
> > +cpu_x86_dump_seg_cache(CPUX86State *env, GString *buf,
> >                         const char *name, struct SegmentCache *sc)
> >  {
> >  #ifdef TARGET_X86_64
> >      if (env->hflags & HF_CS64_MASK) {
> > -        qemu_fprintf(f, "%-3s=%04x %016" PRIx64 " %08x %08x", name,
> > -                     sc->selector, sc->base, sc->limit,
> > -                     sc->flags & 0x00ffff00);
> > +        g_string_append_printf(buf, "%-3s=%04x %016" PRIx64 " %08x %08x", 
> > name,
> > +                               sc->selector, sc->base, sc->limit,
> > +                               sc->flags & 0x00ffff00);
> 
> Did you consider using open_memstream() to get a FILE* that can then
> be passed into these callbacks unchanged, rather than rewriting all
> the callbacks to a new signature?

That is certainly an option, but it wouldn't eliminate the need to do
a rewrite. I would still want to replace qemu_fprintf with fprintf in
that scenario. It is desirable to be able to eliminate the QEMU
specific printf wrappers which only exist because they need to treat
a NULL FILE* object as an indication to output to the HMP chardev.
Admittedly that would result in shorter lines than today.

> Then again, I like the GString signature better than FILE*, even if it
> makes for longer lines.

Yes, the verbosity is not ideal. I like the GString API as a general
purpose API for formatting text output to a buffer overall.

I don't feel too strongly either way though, as long as we get to a place
where we eliminate the custom QEMU printf wrappers that integrate with
the monitor APIs.

Regards,
Daniel
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