On Wed, 2009-05-20 at 16:00 +1000, 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-td23049044.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. It'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.
No but gdb can use the DABR emulation and single step would be busted too. GDB internally heavily uses single step in places you wouldn't expect it to :-) Like I think when breaking on main, it sometimes single step the whole init process of the executable until it hits it. At least I've seen it do that when I was debugging the debug support for 64-bit Book3E. Cheers, Ben. > > On Wed, May 20, 2009 at 5:23 AM, David Gibson > > <da...@gibson.dropbear.id.au> 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. This > > >> 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 having > > >> 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==0. > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
