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List:       linux-kernel
Subject:    Re: [PATCH] Start of compat32.h (again)
From:       Ralf Baechle <ralf () linux-mips ! org>
Date:       2002-11-30 20:34:31
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On Wed, Nov 27, 2002 at 09:29:18AM +0100, Andi Kleen wrote:

> > That is not a safe assumption.  The ia64 ABI requires that a 32-bit
> > result is returned in the least-significant 32 bits only---the upper
> > 32 bits may contain garbage.  It should be safe to declare the syscall
> > return type always as "long", no?
> 
> But the 32bit user space surely doesn't care about any garbage in 
> the upper 32bits, no ?

It does.  With very few exceptions all 32-bit instructions on MIPS require
that all the register values are properly sign extended to 64-bit or the
operation of those instructions is undefined.

  Ralf
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