* Anyone used KDB single-stepping on ARM
@ 2011-10-12 17:41 Tim Bird
2011-12-13 19:41 ` [Kgdb-bugreport] " Jason Wessel
0 siblings, 1 reply; 3+ messages in thread
From: Tim Bird @ 2011-10-12 17:41 UTC (permalink / raw)
To: linux-arm-kernel
I've tried to use single-stepping ('ss' command) on ARM
from KDB, without success.
Has anyone done this - is it currently supported on ARM?
-- Tim
=============================
Tim Bird
Architecture Group Chair, CE Workgroup of the Linux Foundation
Senior Staff Engineer, Sony Network Entertainment
=============================
^ permalink raw reply [flat|nested] 3+ messages in thread* [Kgdb-bugreport] Anyone used KDB single-stepping on ARM
2011-10-12 17:41 Anyone used KDB single-stepping on ARM Tim Bird
@ 2011-12-13 19:41 ` Jason Wessel
2011-12-13 21:56 ` Tim Bird
0 siblings, 1 reply; 3+ messages in thread
From: Jason Wessel @ 2011-12-13 19:41 UTC (permalink / raw)
To: linux-arm-kernel
On 10/12/2011 12:41 PM, Tim Bird wrote:
> I've tried to use single-stepping ('ss' command) on ARM
> from KDB, without success.
>
> Has anyone done this - is it currently supported on ARM?
It is only supported via patches that are not in the mainline kernel the same is also true of the MIPS architecture.
The last consideration I had taken a look at was to consider using the kprobes for single stepping, assuming kprobes work ok on ARM, vs using emulation of single stepping with breakpoints.
The other possibility for newer arm hardward (v7 and up) is to use the hw_breakpoint API and plumb it into kdb/kgdb via the arch/arm/kernel/kgdb.c. It is probably time to take another look at this now since it was merged to the mainline in the last year.
Jason.
^ permalink raw reply [flat|nested] 3+ messages in thread* [Kgdb-bugreport] Anyone used KDB single-stepping on ARM
2011-12-13 19:41 ` [Kgdb-bugreport] " Jason Wessel
@ 2011-12-13 21:56 ` Tim Bird
0 siblings, 0 replies; 3+ messages in thread
From: Tim Bird @ 2011-12-13 21:56 UTC (permalink / raw)
To: linux-arm-kernel
On 12/13/2011 11:41 AM, Jason Wessel wrote:
> On 10/12/2011 12:41 PM, Tim Bird wrote:
>> I've tried to use single-stepping ('ss' command) on ARM
>> from KDB, without success.
>>
>> Has anyone done this - is it currently supported on ARM?
>
> It is only supported via patches that are not in the mainline kernel the same is also true of the MIPS architecture.
>
> The last consideration I had taken a look at was to consider using the kprobes for single stepping, assuming kprobes work ok on ARM, vs using emulation of single stepping with breakpoints.
>
> The other possibility for newer arm hardward (v7 and up) is to use the hw_breakpoint API and plumb it into kdb/kgdb via the arch/arm/kernel/kgdb.c. It is probably time to take another look at this now since it was merged to the mainline in the last year.
OK. Thanks very much for the response. I started looking at it myself,
and it looked too complicated for me to tackle without a lot
more research. My understanding is that older ARM hardware
(pre-V7) doesn't have single-step support, which appears
to match what you're saying above.
If you or someone else works on this, let me know. I'd be a willing
tester. But I probably don't have enough cycles (or experience with kdb/kgdb)
to actually implement this myself.
-- Tim
=============================
Tim Bird
Architecture Group Chair, CE Workgroup of the Linux Foundation
Senior Staff Engineer, Sony Network Entertainment
=============================
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2011-10-12 17:41 Anyone used KDB single-stepping on ARM Tim Bird
2011-12-13 19:41 ` [Kgdb-bugreport] " Jason Wessel
2011-12-13 21:56 ` Tim Bird
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