Scott Wood <scottw...@freescale.com> wrote on 2012/06/01 00:16:53: > > On 05/31/2012 05:14 PM, Joakim Tjernlund wrote: > > 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 :) > > I was thinking more along the lines of someone who's more familiar with > the relevant parts of the code confirming that it's really OK, not just > testing that it doesn't blow up in my face.
Still needs a test run, just throw it in :) _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
