[RFC] [PATCH] powerpc: Add MSR_DE to MSR_KERNEL

[Joakim Tjernlund]

Abatron Support <support at 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.

 Jocke