pt_regs.dbcr0/1

[Paul Mackerras]

Dan Malek writes:

> I believe they were moved because those registers are copied between
> the application context and the debugger.  I was part of making this
> work, but not for moving the registers :-)  IIRC, the reason was we
> wanted gdb to be '4xx-aware' so it could use more of the debug capabilities.

So has anyone done a 4xx-aware gdb yet?

> > If not, they are going.  If so, we can discuss it.
>
> You just can't toss them, they have to be context switched, but I think
> the thread struct is the proper place.  There are always problems with

I wasn't suggesting to get rid of them completely, I was saying that
they should not be in pt_regs.  I think we are in violent agreement. :)

> trying to run any combination of background debuggers, kgdb, or application
> gdb at the same time, which raises the discussion as to where these
> registers should be context switched.  I think we just resign ourselves
> to only one debug interface active at a time and simplify the kernel.

I think so too.  I think it will be basically impossible to do gdb +
external debugging or xmon/kgdb + external debugging.  gdb + xmon/kgdb
may be possible but we will have to see how complex it looks once we
know what the kernel support for gdb looks like.

Paul.

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