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Re: Porting DTrace to ARM

On Mar 7, 2014, at 2:27 AM, Ryota Ozaki <> 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
> The full patch is available at the usual place:
> Best regards,
>  ozaki-r

In undefined_init, the KDTRACE_HOOK should be after und_ev.ev_count++.

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.

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