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Re: 64-bit and N32 kernel interfaces

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Subject: Re: 64-bit and N32 kernel interfaces
From: Daniel Jacobowitz <dan@debian.org>
Date: Thu, 5 Sep 2002 12:19:33 -0400
Cc: Hartvig Ekner <hartvige@mips.com>, "Kevin D. Kissell" <kevink@mips.com>, Tor Arntsen <tor@spacetec.no>, Carsten Langgaard <carstenl@mips.com>, Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
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On Thu, Sep 05, 2002 at 06:16:49PM +0200, Maciej W. Rozycki wrote:
> On Thu, 5 Sep 2002, Daniel Jacobowitz wrote:
> 
> > N32 supports saving and restoring 64-bit registers, which O32 doesn't -
> > according to some comments in GCC, O32 is in fact incompatible with
> > using 64-bit operations.
> 
>  But that old software wouldn't benefit as it didn't perform 64-bit
> operations unless manually coded in software using narrower data types. 
> There is no 64-bit C data type for o32 and long long is quite a recent
> invention -- it didn't exist in the 80s or even early 90s. 

Right.  You don't recompile and get a magic bullet speed improvement
(well, you do, but not a drastic one I think); but you don't recompile
and get a magic bullet binary incompatibility either.  Then you add
64-bit pieces by hand as necessary.

That's my understanding anyway.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

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