From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 In-Reply-To: <20090520060014.GL6333@yookeroo.seuss> References: <6213bc560905190608j73f4191fxbd94158a2b1740c0@mail.gmail.com> <20090519235302.GA6333@yookeroo.seuss> <6213bc560905192250w4caa84aem9c0dedb2eed72fea@mail.gmail.com> <20090520060014.GL6333@yookeroo.seuss> Date: Wed, 20 May 2009 11:44:20 +0530 Message-ID: <6213bc560905192314i2bf7e246r33c6edce9a2669f9@mail.gmail.com> Subject: Re: Initialize DBCR0 for PPC440 targets From: srikanth krishnakar To: srikanth krishnakar , Linuxppc-dev@ozlabs.org Content-Type: text/plain; charset=ISO-8859-1 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi David, Just to correct the statements : How the DBCR0 is initialized on targets that don't use boot loaders ? -Srikant On Wed, May 20, 2009 at 11:30 AM, David Gibson wrote: > On Wed, May 20, 2009 at 11:20:46AM +0530, srikanth krishnakar wrote: >> Hi David, >> >> I am not sure how the IDM behaves on few of PPC440 targets which don't >> have boot loaders. I have a reference for your question: >> >> http://www.nabble.com/Question-about-DBCR0-initialization-for-440-td2304= 9044.html >> >> Without this fix (given patch) I am facing problems with GDB, and >> further target hangs while running gdbserver ! > > That doesn't answer my question. =A0It's not enough to say "this fixes a > problem" you need to explain *how* it fixes the problem. > > And I don't see why IDM would have any effect on *software* > breakpoints. > >> On Wed, May 20, 2009 at 5:23 AM, David Gibson >> wrote: >> > On Tue, May 19, 2009 at 06:38:53PM +0530, srikanth krishnakar wrote: >> >> Hi, >> >> >> >> kernel- 2.6.29 >> >> Debug technique: KGDB >> >> >> >> The PowerPC kernel does not initialize the PPC440 DBCR0 register. Thi= s >> >> prevents the use of software breakpoints in case of internal debug >> >> mode. Looking into head_fsl_booke.S for initialization of DBCR0 is >> >> used by boot-loaders. >> >> It seems head_44x.S lacks this step of DBCR0 register initialization. >> >> So fixing this with initializing the DBCR0 register as shown below : >> >> >> >> Subject: [PATCH] powerpc: 44x: Initialize DBCR0 for targets not havin= g >> >> bootloader >> >> >> >> The kernel does not initialize the PPC440 DBCR0 register. >> >> This prevents (among other things) the use of software >> >> breakpoints with GDB. The boot loaders probably do initialize >> >> this but few targets run without a boot loader >> > >> > Um.. how does this prevent the use of software breakpoints with gdb? >> > The trap instructions still work with IDM=3D=3D0. > > -- > David Gibson =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| I'll have my music = baroque, and my code > david AT gibson.dropbear.id.au =A0| minimalist, thank you. =A0NOT _the_ _= other_ > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| _way_ _a= round_! > http://www.ozlabs.org/~dgibson > --=20 "The Good You Do, The Best You GET" Regards Srikanth Krishnakar **********************