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Date: Mon, 10 Sep 2018 08:30:20 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20180910123020.GA19941@flamenco>
References: <20180903171831.15446-1-cota@braap.org>
	<20180903171831.15446-6-cota@braap.org> <87d0tld83i.fsf@linaro.org>
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Subject: Re: [Qemu-devel] [PATCH 5/6] target/i386/translate: use
 thread-local storage in !user-mode
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To: Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>
Cc: qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Richard Henderson <rth@twiddle.net>, Eduardo Habkost <ehabkost@redhat.com>

On Mon, Sep 10, 2018 at 10:17:53 +0100, Alex Bennée wrote:
> 
> Emilio G. Cota <cota@braap.org> writes:
> 
> > Needed for MTTCG.
> >
> > Signed-off-by: Emilio G. Cota <cota@braap.org>
> > ---
> >  target/i386/translate.c | 24 ++++++++++++++++--------
> >  1 file changed, 16 insertions(+), 8 deletions(-)
> >
> > diff --git a/target/i386/translate.c b/target/i386/translate.c
> > index 1f9d1d9b24..9a6a72e205 100644
> > --- a/target/i386/translate.c
> > +++ b/target/i386/translate.c
> > @@ -71,26 +71,34 @@
> >  
> >  //#define MACRO_TEST   1
> >  
> > +/* we need thread-local storage for mttcg */
> > +#ifdef CONFIG_USER_ONLY
> > +#define I386_THREAD
> > +#else
> > +#define I386_THREAD __thread
> > +#endif
> > +
> 
> I'm confused - as we can have multi-threaded user space don't the same
> requirements apply?

In user-mode, code generation is serialized by mmap_lock.
Making these per-thread would just waste TLS space.

		E.