>From shaggy at linux.vnet.ibm.com Tue Jan 19 08:57:04 2010
From: shaggy at linux.vnet.ibm.com (Dave Kleikamp)
Date: Mon, 18 Jan 2010 14:57:04 -0700
Subject: [RFC:PATCH 00/03] powerpc: Expose BookE debug registers through
extended ptrace interface
Message-ID: <20100118215704.15684.60646.sendpatch...@norville.austin.ibm.com>
> These patches implement an extention to the ptrace interface proposed by
> Thiago Bauermann and the the PowerPC gdb team.
(Using the plain text from mail archive..mail may not be in the usual
mail-reply format...kindly bear).
Hi,
First of all, thanks for bringing this patch that puts the debug
registers in BookE to good use! I learnt about this patch submission
only recently...please see some of my concerns as under.
Given that there now exists generic kernel interfaces to use
hw-breakpoints - register_user_hw_breakpoint() and
unregister_hw_breakpoint() (available in mainline since 2.6.33-rc1), it
would be prudent to use them for the ptrace requests (that are made in
arch_ptrace()).
This would mean that some of the arch-specific debug register code that
read/write from/to the debug registers of Book-E may have to be in a
form that closely resembles arch/<x86><power>/kernel/hw_breakpoint.c
A patch that enables arch-specific code for PPC64 is already submitted
(linuxppc-dev ref: 20100121084640.ga3...@in.ibm.com). This converts
ptrace requests for PTRACE_<GET><SET>_DEBUGREG flags to use the
above-mentioned interfaces for PPC64.
If you intend to re-write this patch to use the generic hw-breakpoint
interfaces (which I strongly recommend you to do, for the reasons mentioned
below), I would be more than glad to help you port them.
Some of the benefits of using these generic interfaces include:
- Interoperability with other users of debug register (such as parallel
kernel requests) i.e. non-exclusive use of debug registers.
- Enables debugging/tracing tools such as perf-events and ftrace to make
use of debug registers.
- Re-use of common code available in kernel (kernel/hw_breakpoint.c).
Let me know what you think.
Thanks,
K.Prasad
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
