Re: Porting DTrace to ARM

[Ryota Ozaki <ozaki-r%NetBSD.org@localhost>]

On Sat, Mar 8, 2014 at 12:51 AM, Matt Thomas <matt%3am-software.com@localhost> 
wrote:
>
> On Mar 7, 2014, at 2:27 AM, Ryota Ozaki <ozaki-r%NetBSD.org@localhost> wrote:
>
>> Hi Matt,
>>
>> So my patch for sys/arch/arm is now rather small than
>> so far (just two files); it's minimum code for the core part
>> to run DTrace on ARM.
>>
>> Can you please check it?
>>
>> The patch for sys/arch/arm is
>> http://www.netbsd.org/~ozaki-r/dtrace-arm-sys.patch
>> The full patch is available at the usual place:
>> https://gist.github.com/ozaki-r/8535846
>>
>> Best regards,
>>  ozaki-r
>
> In undefined_init, the KDTRACE_HOOK should be after und_ev.ev_count++.

I see. Fixed.

Any other problem?

>
> Digression ahead.
>
> I wonder if it wouldn't be better to use a BKPT instruction on armv5t
> and later and avoid the undefined trap, and use a prefetch abort with
> a known FSR code.  For pre-armv5t, we'd need a undefined handler but
> we have one of those now.  BKPT instructions have either a 16-bit (ARM)
> or 8-bit (thumb) value encoded within.
>
> But that can be tackled later.

Actually this is not so digression because my next target is armv5t...

Anyway thanks a lot for checking!
  ozaki-r