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Re: GCCFLAGS for gcc 3.3.x (-march and _MIPS_ISA)

To: linux-mips@linux-mips.org
Subject: Re: GCCFLAGS for gcc 3.3.x (-march and _MIPS_ISA)
From: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Date: Thu, 14 Aug 2003 05:08:41 +0200
In-reply-to: <Pine.GSO.3.96.1030812163438.7029F-100000@delta.ds2.pg.gda.pl>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20030812140452.GD10792@rembrandt.csv.ica.uni-stuttgart.de> <Pine.GSO.3.96.1030812163438.7029F-100000@delta.ds2.pg.gda.pl>
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Maciej W. Rozycki wrote:
> On Tue, 12 Aug 2003, Thiemo Seufer wrote:
> 
> > > > If the intention is to use mfc0 for 32bit kernels and dmfc0 for 64bit,
> > > > the check should probably be
> > > > 
> > > > #ifdef __mips64
> > > > # define MFC0           dmfc0
> > > > # define MTC0           dmtc0
> > > > #else
> > > > # define MFC0           mfc0
> > > > # define MTC0           mtc0
> > > > #endif
> > > 
> > >  I'd go for CONFIG_MIPS64 here.
> > 
> > This would work as well, but I prefer compiler intrinsic defines
> > over custom configury.
> 
>  Well, for Linux it seems appropriate to use a kernel's configuration to
> select run-time behaviour -- in this case it's CONFIG_MIPS64 that was
> selected by a user that matters (i.e. that we use 64-bit addressing) and
> not a compiler's configuration.  Just the opposite to what's expected in
> the userland. 

JFTR:
__mips64 denotes neither 64-bit addressing nor the compiler configuration.
It just means that the generated code uses 64 bit wide registers.


Thiemo

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