Re: [PATCH] [RFC] [2.5 i386] GCC 3.1 -march support, PPRO_FENCE

Luca Barbieri (ldb@ldb.ods.org)
04 Aug 2002 22:43:34 +0200


--=-ZIqX+Wv+3nph8wzv60Tk
Content-Type: text/plain
Content-Transfer-Encoding: 7bit

On Sun, 2002-08-04 at 23:54, Alan Cox wrote:
> On Sun, 2002-08-04 at 21:23, Luca Barbieri wrote:
> > Added, with the exception that sfence is only used if CONFIG_X86_OOSTORE
> > is not defined (currently never).
>
> Ok sorry I follow what you are doing. What I don't understand is why you
> are generating unneeded sfence/mfence instructions in the other cases ?
It was my fault: I explained it incorrectly. sfence is only used if both
CONFIG_X86_OOSTORE and CONFIG_MMXEXT are set, which currently never
happens with the existing processors.

> When we use MMX/SSE we need the view to be consistent anyway so the
> various copying routines already handle this internally.
That's why sfence is not used unless CONFIG_X86_OOSTORE (and
CONFIG_X86_MMXEXT) is defined.
mfence and lfence instead replace the "lock; addl $0,0(%%esp)". Is this
wrong?

--=-ZIqX+Wv+3nph8wzv60Tk
Content-Type: application/pgp-signature; name=signature.asc
Content-Description: This is a digitally signed message part

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.7 (GNU/Linux)

iD8DBQA9TZH2djkty3ft5+cRAoToAJ9cNPcdFzbL2ey+OH6mpNjgvnuUzACgr4bP
cdRy7ge1Rg47HdYfnVOpKi4=
=sCwe
-----END PGP SIGNATURE-----

--=-ZIqX+Wv+3nph8wzv60Tk--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/