[RFC:PATCH 00/03] powerpc: Expose BookE debug registers through extended ptrace interface

Kumar Gala galak at kernel.crashing.org
Fri Dec 11 13:45:02 EST 2009

On Dec 10, 2009, at 9:57 AM, Dave Kleikamp wrote:

> These patches implement an extention to the ptrace interface proposed by
> Thiago Bauermann and the the PowerPC gdb team.
> GDB intends to support the following hardware debug features of BookE
> processors:
> 4 hardware breakpoints (IAC)
> 2 hardware watchpoints (read, write and read-write) (DAC)
> 2 value conditions for the hardware watchpoints (DVC)
> For that, we need to extend ptrace so that GDB can query and set these
> resources. Since we're extending, we're trying to create an interface
> that's extendable and that covers both BookE and server processors, so
> that GDB doesn't need to special-case each of them. We propose the
> following 3 new ptrace requests described below.
> There have been discussions of a generic hardware debug interface for the
> kernel which would hopefully contemplate all the functionality below and
> supersede it.  But we need something that works now, and which enables GDB
> to be simpler and work with both Server and Embedded processors without
> special cases.

What do we do in EDM mode?  We need a flag somewhere to determine if HW supports conveying DBCR0[EDM] and if it does which of the ptrace calls fails?

- k

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