Re: Bug#539378: [hppa]: fails to load nfs module: Global Offset Table

From: John David Anglin <dave@hiauly1.hia.nrc.ca>
To: Carlos O'Donell <carlos@systemhalted.org>
Cc: Helge Deller <deller@gmx.de>,
	kyle@mcmartin.ca, elendil@planet.nl, 539378@bugs.debian.org,
	debian-hppa@lists.debian.org, linux-parisc@vger.kernel.org,
	randolph@tausq.org, submit@bugs.debian.org
Subject: Re: Bug#539378: [hppa]: fails to load nfs module: Global Offset Table
Date: Sat, 1 Aug 2009 09:53:20 -0400	[thread overview]
Message-ID: <20090801135319.GA13949@hiauly1.hia.nrc.ca> (raw)
In-Reply-To: <119aab440907311851t502a208bh34b21b3f732e3e09@mail.gmail.com>

On Fri, 31 Jul 2009, Carlos O'Donell wrote:

> >> + =A0 =A0 =A0 =A0 =A0 =A0 if (d <=3D 15)
> >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 stub->insns[0] |=3D reas=
semble_14(d);
> >
> > reassemble_14 is wrong for ldd format 3. =A0Need format 5 and im5 i=
nsertion.
>=20
> This is using reassemble_14 for ldd format 5, which is correct.

Huh?  Format 5 has a five bit immediate and it's not compatible with
reassemble_14.  The value is actually being stuffed into a format 3 ldd
pattern (i.e., format 3 is being used for displacements 0 and 8).

If format 3 is going to be used for short displacements, then use
reassemble_16a as it is the inverse to the assemble_16a operation
described in the arch.  Using reassemble_14 with ldd is confusing.

As you pointed out, the arch shows using format 5 for short displacemen=
ts.
It's unclear whether there is a performance or functional difference as=
ide
from the behavior of space selection.  There may be no requirement for
hardware to implement short displacements using format 3.

Dave
--=20
J. David Anglin                                  dave.anglin@nrc-cnrc.g=
c.ca
National Research Council of Canada              (613) 990-0752 (FAX: 9=
52-6602)
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