From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=60736 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OOp18-0002Gw-2U for qemu-devel@nongnu.org; Wed, 16 Jun 2010 05:34:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OOp16-0006ii-K3 for qemu-devel@nongnu.org; Wed, 16 Jun 2010 05:34:41 -0400 Received: from fmmailgate02.web.de ([217.72.192.227]:60565) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OOp16-0006iX-8F for qemu-devel@nongnu.org; Wed, 16 Jun 2010 05:34:40 -0400 Message-ID: <4C189AAC.8040502@web.de> Date: Wed, 16 Jun 2010 11:34:36 +0200 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [Bug 581353] Re: qemu doesn't stop execution upon hitting a breakpoint References: <20100516152304.10489.35592.malonedeb@potassium.ubuntu.com> <20100616070748.20899.45040.malone@wampee.canonical.com> <4C187FD7.5080601@web.de> <4C188203.5060402@web.de> <4C18852C.5010209@web.de> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig661EE61E1D8976EABA05B851" Sender: jan.kiszka@web.de List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: malc Cc: chimeranet89@gmail.com, qemu-devel@nongnu.org, Jun Koi This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig661EE61E1D8976EABA05B851 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable malc wrote: > On Wed, 16 Jun 2010, Jan Kiszka wrote: >=20 >> Jun Koi wrote: >>> On Wed, Jun 16, 2010 at 4:49 PM, Jan Kiszka wrote= : >>>> Jun Koi wrote: >>>>> On Wed, Jun 16, 2010 at 4:40 PM, Jan Kiszka wro= te: >>>>>> Jun Koi wrote: >>>>>>> On Wed, Jun 16, 2010 at 4:07 PM, Alfredo Mungo wrote: >>>>>>>> Same thing happens to me, same versions as above.. I must turn t= o >>>>>>>> another app to accomplish my work while awaiting for a bug-fix, = the code >>>>>>>> is perfectly executed but while gdb hits the breakpoints qemu go= es on.. >>>>>>>> >>>>>>>> -- >>>>>>>> qemu doesn't stop execution upon hitting a breakpoint >>>>>>>> https://bugs.launchpad.net/bugs/581353 >>>>>>>> You received this bug notification because you are a member of q= emu- >>>>>>>> devel-ml, which is subscribed to QEMU. >>>>>>> i think this bug has been fixed in 0.12.4. have you tried that?? >>>>>> Or this is a well-known gdb deficit: if the bootloader operates in= >>>>>> real-mode, you have to set two breakpoints, one at the linear addr= ess to >>>>>> make qemu catch it, and another one at the segment offset to avoid= gdb >>>>>> skipping the exit due to ip !=3D bp-addr. >>>>>> >>>>>> gdb is still fairly restricted when it comes to system-level debug= ging, >>>>>> specifically as it lacks support for special x86 registers and the= >>>>>> segmented addressing mode. >>>>> what do you mean by "it lacks support for special x86 registers" ? >>>> idtr, gdtr, ldtr, tr, crX - to name the most important ones. >>> do you mean gdb has no command to show the values of these registers?= >>> or you mean it doenst have anyway to get notified when these register= s >>> are modified? (i dont see how this is useful for debugging, anway) >> Both: Neither supports gdb them as part of its register set nor does t= he >> remote gdb protocol transport them. >> >> You need this for segmented addressing, either in real mode (linear >> address =3D segment * 16 + offset) or in segmented protected mode (les= s >=20 > Not true in general (big real mode), CPU still references hidden segmen= t > cache even when protection is enabled. Unfortunately, the BIOS does not start in big real mode e.g... Jan >=20 >> common in modern OSes, but at least still used for per-CPU variables i= n >> Linux). And you need a way to detect the current operation mode at all= >> to switch between 16/32, and 64 bit registers (set arch i386 vs. >> i386:x86-64). You don't need all this for application-level debugging,= >> and that's why gdb lacks it so far. >> >> Jan >> >> --------------enig661EE61E1D8976EABA05B851 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkwYmq0ACgkQitSsb3rl5xSF7wCdG1dSq1xMNcPuIrysscgrApRB 4c4AoIa9NgWYRwKRVw5uF8kbu/KO+Fj4 =qXYx -----END PGP SIGNATURE----- --------------enig661EE61E1D8976EABA05B851--