[PATCH 03/31] Add debugger entry points for AVR32

[PATCH 03/31] Add debugger entry points for AVR32

[Jeffrey Merkey]

This patch series adds an export which can be set by system debuggers to
direct the hard lockup and soft lockup detector to trigger a breakpoint
exception and enter a debugger if one is active.  It is assumed that if
someone sets this variable, then an breakpoint handler of some sort will
be actively loaded or registered via the notify die handler chain.

This addition is extremely useful for debugging hard and soft lockups
real time and quickly from a console debugger.

Signed-off-by: Jeffrey Merkey <jeffmerkey@gmail.com>
---
 arch/avr32/include/asm/kdebug.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/avr32/include/asm/kdebug.h b/arch/avr32/include/asm/kdebug.h
index f930ce2..f67caf0 100644
--- a/arch/avr32/include/asm/kdebug.h
+++ b/arch/avr32/include/asm/kdebug.h
@@ -1,6 +1,10 @@
 #ifndef __ASM_AVR32_KDEBUG_H
 #define __ASM_AVR32_KDEBUG_H
 
+static inline void arch_breakpoint(void)
+{
+}
+
 /* Grossly misnamed. */
 enum die_val {
 	DIE_BREAKPOINT,
-- 
1.8.3.1

Re: [PATCH 03/31] Add debugger entry points for AVR32

[Hans-Christian Noren Egtvedt]

Around Thu 28 Jan 2016 12:46:17 -0700 or thereabout, Jeffrey Merkey wrote:
> This patch series adds an export which can be set by system debuggers to
> direct the hard lockup and soft lockup detector to trigger a breakpoint
> exception and enter a debugger if one is active.  It is assumed that if
> someone sets this variable, then an breakpoint handler of some sort will
> be actively loaded or registered via the notify die handler chain.
> 
> This addition is extremely useful for debugging hard and soft lockups
> real time and quickly from a console debugger.
> 
> Signed-off-by: Jeffrey Merkey <jeffmerkey@gmail.com>

Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>

> ---
>  arch/avr32/include/asm/kdebug.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/avr32/include/asm/kdebug.h b/arch/avr32/include/asm/kdebug.h
> index f930ce2..f67caf0 100644
> --- a/arch/avr32/include/asm/kdebug.h
> +++ b/arch/avr32/include/asm/kdebug.h
> @@ -1,6 +1,10 @@
>  #ifndef __ASM_AVR32_KDEBUG_H
>  #define __ASM_AVR32_KDEBUG_H
>  
> +static inline void arch_breakpoint(void)
> +{
> +}

Will not this just be optimized away? Are you expecting other developers to
add a no-op assembler instruction into this function body?

<snipp>
-- 
Best regards, Hans-Christian Egtvedt

Re: [PATCH 03/31] Add debugger entry points for AVR32

[Jeffrey Merkey]

On 1/28/16, Hans-Christian Noren Egtvedt <egtvedt@samfundet.no> wrote:
> Around Thu 28 Jan 2016 12:46:17 -0700 or thereabout, Jeffrey Merkey wrote:
>> This patch series adds an export which can be set by system debuggers to
>> direct the hard lockup and soft lockup detector to trigger a breakpoint
>> exception and enter a debugger if one is active.  It is assumed that if
>> someone sets this variable, then an breakpoint handler of some sort will
>> be actively loaded or registered via the notify die handler chain.
>>
>> This addition is extremely useful for debugging hard and soft lockups
>> real time and quickly from a console debugger.
>>
>> Signed-off-by: Jeffrey Merkey <jeffmerkey@gmail.com>
>
> Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
>
>> ---
>>  arch/avr32/include/asm/kdebug.h | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/avr32/include/asm/kdebug.h
>> b/arch/avr32/include/asm/kdebug.h
>> index f930ce2..f67caf0 100644
>> --- a/arch/avr32/include/asm/kdebug.h
>> +++ b/arch/avr32/include/asm/kdebug.h
>> @@ -1,6 +1,10 @@
>>  #ifndef __ASM_AVR32_KDEBUG_H
>>  #define __ASM_AVR32_KDEBUG_H
>>
>> +static inline void arch_breakpoint(void)
>> +{
>> +}
>
> Will not this just be optimized away? Are you expecting other developers to
> add a no-op assembler instruction into this function body?
>
> <snipp>
> --
> Best regards, Hans-Christian Egtvedt
>

Yes, I am hoping the maintainers of each arch to make a decision about
how they wish to implement this and/or change it.  Totally up to you
guys.  I need it stubbed in all the arches so it passes test robot
builds for watchdog.c.

Jeff