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Date: Thu, 18 Jun 2015 11:29:00 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2 0/3] Fix exceptions handling for MIPS
 and i386
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To: Aurelien Jarno <aurelien@aurel32.net>, Pavel Dovgaluk <Pavel.Dovgaluk@ispras.ru>
Cc: rth7680@gmail.com, leon.alrae@imgtec.com, qemu-devel@nongnu.org

On 18/06/2015 11:08, Aurelien Jarno wrote:
> For an i386 guest still on an x86 host, I get a 4% slower boot time by
> not using retranslation (see patch below). This is not that much
> compared to the complexity retranslation bring us.

QEMU could just always compute and store the restore_state information.
 TCG needs to help filling it in (a new TCG opcode?), but it should be ea=
sy.

Paolo

> diff --git a/target-i386/translate.c b/target-i386/translate.c
> index 58b1959..de65bba 100644
> --- a/target-i386/translate.c
> +++ b/target-i386/translate.c
> @@ -8001,6 +8001,9 @@ static inline void gen_intermediate_code_internal=
(X86CPU *cpu,
> =20
>      gen_tb_start(tb);
>      for(;;) {
> +        gen_update_cc_op(dc);
> +        gen_jmp_im(pc_ptr - dc->cs_base);
> +
>          if (unlikely(!QTAILQ_EMPTY(&cs->breakpoints))) {
>              QTAILQ_FOREACH(bp, &cs->breakpoints, entry) {
>                  if (bp->pc =3D=3D pc_ptr &&
> diff --git a/translate-all.c b/translate-all.c
> index b6b0e1c..3d4c017 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -212,6 +212,8 @@ static int cpu_restore_state_from_tb(CPUState *cpu,=
 TranslationBlock *tb,
>      int64_t ti;
>  #endif
> =20
> +    return -1;
> +
>  #ifdef CONFIG_PROFILER
>      ti =3D profile_getclock();
>  #endif