From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gdb-patches-return-76101-listarch-gdb-patches=sources.redhat.com@sourceware.org>
Received: (qmail 27076 invoked by alias); 16 Oct 2010 20:16:45 -0000
Received: (qmail 27068 invoked by uid 22791); 16 Oct 2010 20:16:44 -0000
X-SWARE-Spam-Status: No, hits=-1.8 required=5.0	tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,TW_EG
X-Spam-Check-By: sourceware.org
Received: from mail-vw0-f41.google.com (HELO mail-vw0-f41.google.com) (209.85.212.41)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sat, 16 Oct 2010 20:16:39 +0000
Received: by vws19 with SMTP id 19so1106434vws.0        for <gdb-patches@sourceware.org>; Sat, 16 Oct 2010 13:16:38 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.220.187.75 with SMTP id cv11mr466055vcb.169.1287260198004; Sat, 16 Oct 2010 13:16:38 -0700 (PDT)
Received: by 10.220.181.138 with HTTP; Sat, 16 Oct 2010 13:16:37 -0700 (PDT)
In-Reply-To: <201010162100.47407.pedro@codesourcery.com>
References: <20100203174414.GA29948@lucon.org>	<201009282123.29913.pedro@codesourcery.com>	<AANLkTim6oLv-WqasLRfxG=tf3QVFj=hP=Nn1U0KGovcm@mail.gmail.com>	<201010162100.47407.pedro@codesourcery.com>
Date: Sat, 16 Oct 2010 20:16:00 -0000
Message-ID: <AANLkTi=BEHZKetmGy10n0G_B4RvbEO53Bw5xDAiQN=0=@mail.gmail.com>
Subject: Re: PATCH: gdbserver: Clear regcache if buf is NULL
From: "H.J. Lu" <hjl.tools@gmail.com>
To: Pedro Alves <pedro@codesourcery.com>
Cc: gdb-patches@sourceware.org
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: quoted-printable
X-IsSubscribed: yes
Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <gdb-patches.sourceware.org>
List-Subscribe: <mailto:gdb-patches-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/gdb-patches/>
List-Post: <mailto:gdb-patches@sourceware.org>
List-Help: <mailto:gdb-patches-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: gdb-patches-owner@sourceware.org
X-SW-Source: 2010-10/txt/msg00266.txt.bz2

On Sat, Oct 16, 2010 at 1:00 PM, Pedro Alves <pedro@codesourcery.com> wrote:
> On Friday 01 October 2010 02:51:07, H.J. Lu wrote:
>> On Tue, Sep 28, 2010 at 1:23 PM, Pedro Alves <pedro@codesourcery.com> wr=
ote:
>
>> > Hi H.J.. =A0I'm looking at where in the current sources this
>> > ended up being used, and not finding it. =A0Am I right in thinking
>> > that the need for this was obsoleted when you later tought
>> > gdbserver x86-linux about xml descriptions?
>> >
>>
>> i387-fp.c has
>>
>> =A0 if ((x86_xcr0 & I386_XSTATE_SSE))
>> =A0 =A0 {
>> =A0 =A0 =A0 int xmm0_regnum =3D find_regno ("xmm0");
>>
>> =A0 =A0 =A0 if ((clear_bv & I386_XSTATE_SSE))
>> =A0 =A0 =A0 =A0 p =3D NULL;
>> =A0 =A0 =A0 else
>> =A0 =A0 =A0 =A0 p =3D (char *) buf;
>>
>> =A0 =A0 =A0 for (i =3D 0; i < num_xmm_registers; i++)
>> =A0 =A0 =A0 =A0 {
>> =A0 =A0 =A0 =A0 =A0 if (p)
>> =A0 =A0 =A0 =A0 =A0 =A0 p =3D ((char *) &fp->xmm_space[0]) + i * 16;
>> =A0 =A0 =A0 =A0 =A0 supply_register (regcache, i + xmm0_regnum, p);
>> =A0 =A0 =A0 =A0 }
>> =A0 =A0 }
>>
>
> Thanks, and sorry as for not coming back to this promptly.
> Hmm, I don't think I have a way to trigger that.
> So is the registers' value really zero, or should gdb
> ideally present them as not available (and zero is just a
> hack)?
>

You will see it only on machines with XSAVE and enabled in OS.
Please see

13.6 XSAVE/XRSTOR AND PROCESSOR EXTENDED STATE
MANAGEMENT

in

Intel=AE 64 and IA-32 Architectures Software Developer=92s Manual
Volume 3A: System Programming Guide, Part 1

Basically values in vector registers may not be valid, depending
on vector state.


--=20
H.J.