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. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
