Re: [RFC PATCH 1/5] Rename the singlestep global variable to one_insn_per_tb

[Peter Maydell]

On Mon, 6 Feb 2023 at 20:20, Thomas Huth <thuth@redhat.com> wrote:
>
> On 06/02/2023 18.13, Peter Maydell wrote:
> > The 'singlestep' global variable is badly misnamed, because it has
> > nothing to do with single-stepping the emulation either via the gdb
> > stub or by emulation of architectural debug facilities.  Instead what
> > it does is force TCG to put only one instruction into each TB.
> > Rename it to one_insn_per_tb, so that it reflects what it does better
> > and is easier to search for in the codebase.
> >
> > This misnaming is also present in user-facing interfaces: the command
> > line option '-singlestep', the HMP 'singlestep' command, and the QMP
> > StatusInfo object.  Those are harder to update because we need to
> > retain backwards compatibility.  Subsequent patches will add
> > better-named aliases so we can eventually deprecate-and-drop the old,
> > bad name.
> >
> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> >   include/exec/cpu-common.h   | 2 +-
> >   accel/tcg/cpu-exec.c        | 4 ++--
> >   bsd-user/main.c             | 4 ++--
> >   linux-user/main.c           | 4 ++--
> >   softmmu/globals.c           | 2 +-
> >   softmmu/runstate-hmp-cmds.c | 4 ++--
> >   softmmu/runstate.c          | 2 +-
> >   softmmu/vl.c                | 2 +-
> >   8 files changed, 12 insertions(+), 12 deletions(-)
> >
> > diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
> > index 6feaa40ca7b..f2592a1967f 100644
> > --- a/include/exec/cpu-common.h
> > +++ b/include/exec/cpu-common.h
> > @@ -163,7 +163,7 @@ int cpu_memory_rw_debug(CPUState *cpu, vaddr addr,
> >                           void *ptr, size_t len, bool is_write);
> >
> >   /* vl.c */
> > -extern int singlestep;
> > +extern int one_insn_per_tb;
>
> IMHO the global variable should completely go away - this should get a
> property of the tcg accel instead.

I agree in principle, but this might be tricky because of the
user-mode emulators. I'll have a look.

-- PMM