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Date: Wed, 27 Nov 2002 09:29:18 +0100
From: Andi Kleen <ak@muc.de>
To: davidm@hpl.hp.com
Cc: Stephen Rothwell <sfr@canb.auug.org.au>, Linus <torvalds@transmeta.com>,
       LKML <linux-kernel@vger.kernel.org>, anton@samba.org,
       "David S. Miller" <davem@redhat.com>, ak@muc.de, schwidefsky@de.ibm.com,
       ralf@gnu.org, willy@debian.org
Subject: Re: [PATCH] Start of compat32.h (again)
Message-ID: <20021127082918.GA5227@averell>
References: <20021127184228.2f2e87fd.sfr@canb.auug.org.au> <15844.31669.896101.983575@napali.hpl.hp.com>
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On Wed, Nov 27, 2002 at 09:00:53AM +0100, David Mosberger wrote:
> >>>>> On Wed, 27 Nov 2002 18:42:28 +1100, Stephen Rothwell <sfr@canb.auug.org.au> said:
> 
>   Stephen> I make the follwing assumptions: returning s32 from a 32
>   Stephen> bit compatibility system call is the same as returning long
>   Stephen> or int.
> 
> 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 ?

64bit user space might, but that's not driven by a shared compat layer.

-Andi
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