Scott Wood <scottw...@freescale.com> wrote on 2012/05/31 23:43:34: > > On 05/31/2012 04:38 PM, Joakim Tjernlund wrote: > > Scott Wood <scottw...@freescale.com> wrote on 2012/05/31 19:47:53: > >> > >> On 05/31/2012 04:56 AM, Joakim Tjernlund wrote: > >>> Abatron Support <supp...@abatron.ch> wrote on 2012/05/31 11:30:57: > >>>> > >>>> > >>>>> Abatron Support <supp...@abatron.ch> wrote on 2012/05/30 14:08:26: > >>>>>> > >>>>>>>> I have tested this briefly with BDI2000 on P2010(e500) and > >>>>>>>> it works for me. I don't know if there are any bad side effects, > >>>>>>>> therfore > >>>>>>>> this RFC. > >>>>>> > >>>>>>> We used to have MSR_DE surrounded by CONFIG_something > >>>>>>> to ensure it wasn't set under normal operation. IIRC, if MSR_DE > >>>>>>> is set, you will have problems with software debuggers that > >>>>>>> utilize the the debugging registers in the chip itself. You only want > >>>>>>> to force this to be set when using the BDI, not at other times. > >>>>>> > >>>>>> This MSR_DE is also of interest and used for software debuggers that > >>>>>> make use of the debug registers. Only if MSR_DE is set then debug > >>>>>> interrupts are generated. If a debug event leads to a debug interrupt > >>>>>> handled by a software debugger or if it leads to a debug halt handled > >>>>>> by a JTAG tool is selected with DBCR0_EDM / DBCR0_IDM. > >>>>>> > >>>>>> The "e500 Core Family Reference Manual" chapter "Chapter 8 > >>>>>> Debug Support" explains in detail the effect of MSR_DE. > >>>> > >>>>> So what is the verdict on this? I don't buy into Dan argument without > >>>>> some > >>>>> hard data. > >>>> > >>>> What I tried to mention is that handling the MSR_DE correct is not only > >>>> an emulator (JTAG debugger) requirement. Also a software debugger may > >>>> depend on a correct handled MSR_DE bit. > >>> > >>> Yes, that made sense to me too. How would SW debuggers work if the kernel > >>> keeps > >>> turning off MSR_DE first chance it gets? > >> > >> The kernel selectively enables MSR_DE when it wants to debug. I'm not > >> sure if anything will be bothered by leaving it on all the time. This > >> is something we need for virtualization as well, so a hypervisor can > >> debug the guest. > > > > hmm, I read that as you as in favour of the patch? > > I'd want some confirmation that it doesn't break anything, and that > there aren't any other places that need MSR_DE that this doesn't cover, > but in general yes.
Then you need to test drive the patch :) Jocke _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
