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

Kumar Gala
2009-12-11T02:45:02Z

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.
>=20
> GDB intends to support the following hardware debug features of BookE
> processors:
>=20
> 4 hardware breakpoints (IAC)
> 2 hardware watchpoints (read, write and read-write) (DAC)
> 2 value conditions for the hardware watchpoints (DVC)
>=20
> 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.
>=20
> 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=