From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9013 invoked by alias); 3 Dec 2001 01:24:27 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 8991 invoked from network); 3 Dec 2001 01:24:25 -0000 Received: from unknown (HELO nic.osagesoftware.com) (65.186.161.49) by sources.redhat.com with SMTP; 3 Dec 2001 01:24:25 -0000 Received: from maple.osagesoftware.com (maple.osagesoftware.com [192.168.1.20]) by nic.osagesoftware.com (8.10.1/8.10.1) with ESMTP id fB31OOI24075 for ; Sun, 2 Dec 2001 20:24:24 -0500 Message-Id: <4.3.2.7.2.20011202201853.00bfba30@mail.osagesoftware.com> X-Sender: relson@mail.osagesoftware.com X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Sun, 02 Dec 2001 17:24:00 -0000 To: gdb@sources.redhat.com From: David Relson Subject: Re: Problem with threaded program In-Reply-To: <20011202184904.B7998@nevyn.them.org> References: <3C0A7599.3040902@cygnus.com> <4.3.2.7.2.20011202114313.00c40ab0@mail.osagesoftware.com> <3C0A7599.3040902@cygnus.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-SW-Source: 2001-12/txt/msg00005.txt.bz2 At 06:49 PM 12/2/01, you wrote: >On Sun, Dec 02, 2001 at 01:40:25PM -0500, Andrew Cagney wrote: > > > > > Ah, looks like the GDB is corrupting a threaded programs FP registers > > problem. > > > > I'm 99% certain this is in the thread-db/kernel interface that GDB is > > using. Each time this crops up, the problem gets resolved with a > > kernel/library update. > > > > If someone can point out a definitive explination I'll add it to the > > 5.1.1 PROBLEMS file. That way it is at least clearly documented. > > > > The apparent 4.18 -> 5.0 ``breakage'' would have occured because GDB > > switched to using the thread-db/kernel interface. > >Well, it happens every time we try to step over an fstpl instruction. >We never call any of the SETREGS or POKE variants, only GETREGS and >GETFPXREGS; I don't see how it could really be our bug. > >Note that in the non-threaded case we never call PTRACE_GETFPXREGS at >all. That's: > - an inefficency in the thread code, not surprisingly > - highly suggestive of a kernel bug. > >My money's on the kernel, but I don't have time to debug this just now. Daniel, I don't know what the division of labor is between gdb and the kernel for situations like this, so I can't comment on that. I can report, however, that the problem doesn't occur with gdb-4.18. I had previously tested with an old copy of gdb-4.18. To remove one possible difference, I have tested for the problem using copies of both gdb-4.18 and gdb-5.1 built today under the 2.4.16 kernel. gdb-4.18 works properly and gdb-5.1 shows the problem. If the problem is in the kernel, then 4.18 and 5.1 must be using different capabilities ... David