Re: [PATCH v2 03/29] tcg: Re-order tcg_region_init vs tcg_prologue_init

[Richard Henderson]

On 3/15/21 5:37 PM, Roman Bolshakov wrote:
> >       tcg_exec_init(s->tb_size * 1024 * 1024, s->splitwx_enabled);
> >       mttcg_enabled = s->mttcg_enabled;
> > -
> > -    /*
> > -     * Initialize TCG regions only for softmmu.
> > -     *
> > -     * This needs to be done later for user mode, because the prologue
> > -     * generation needs to be delayed so that GUEST_BASE is already set.
> > -     */
> > -#ifndef CONFIG_USER_ONLY
> > -    tcg_region_init();
>
> Note that tcg_region_init() invokes tcg_n_regions() that depends on
> qemu_tcg_mttcg_enabled() that evaluates mttcg_enabled. Likely you need
> to move "mttcg_enabled = s->mttcg_enabled;" before tcg_exec_init() to
> keep existing behaviour.

Yes indeed.  This gets fixed in patch 12, which is why I didn't notice 
breakage.  Will adjust.

> > -    total_size = s->code_gen_buffer_size;
> > -    s->code_ptr = buf0;
> > -    s->code_buf = buf0;
> > +    tcg_region_assign(s, 0);
> > +    s->code_ptr = s->code_gen_ptr;
> > +    s->code_buf = s->code_gen_ptr;
>
> Pardon me for asking a naive question, what's the difference between
> s->code_buf and s->code_gen_buf and, respectively, s->code_ptr and
> s->code_gen_ptr?

I don't remember.  I actually had it in my mind to rename all of these, remove 
one or two that feel redundant, and document them all.  But the patch set was 
large enough already.


r~