Re: Re[2]: [RFC] [PATCH] powerpc: Add MSR_DE to MSR_KERNEL

Abatron Support [off-list ref] wrote on 2012/05/30 14:08:26:

quoted

quoted

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.

quoted

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