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Re: thread-ready ABIs

To: "H . J . Lu" <hjl@lucon.org>
Subject: Re: thread-ready ABIs
From: Daniel Jacobowitz <dan@debian.org>
Date: Fri, 18 Jan 2002 16:23:25 -0500
Cc: Ulrich Drepper <drepper@redhat.com>, GNU libc hacker <libc-hacker@sources.redhat.com>, linux-mips@oss.sgi.com
In-reply-to: <20020118101908.C23887@lucon.org>
References: <m3elkoa5dw.fsf@myware.mynet> <20020118101908.C23887@lucon.org>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.3.23i
On Fri, Jan 18, 2002 at 10:19:08AM -0800, H . J . Lu wrote:
> > MIPS: Who feels responsible?  Andreas, HJ?
> > 
> 
> I don't see there are any registers we can use without breaking ABI.
> On the other hand, can we change the mips kernel to save k0 or k1 for
> user space?

No, there are no free registers and $k0/$k1 are needed by the kernel
for exceptions.  The only way I can see to do this would be to change
the ABI.

There are none available; the least used that I see is $v1, but $v1 is
used to return half of a double precision return value.  We would have
to steal one of the existing call-saved or call-clobbered registers.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer

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