Low-level trace-buffers in CAM

[John Baldwin]

On Monday, October 26, 2015 09:52:25 PM Adrian Chadd wrote:
> Hi,
> 
> ok. So this is where I create work for people. :-)
> 
> Something I've been tossing up for quite some time is a generic
> version of this that exposes a ring-buffer of entries back to
> userland. For things like this, things like ALQ/KTR, etc, it's all
> just a producer-consumer ring based thing. You don't even care about
> multiple readers; that's a userland thing.
> 
> So, I'm a big fan of this. I did this for the ath driver to debug
> descriptors and register accesses and it was a big help. I'd really
> like to see a more generic way we can expose this data in an efficient
> manner!

I actually think bpf might not be a bad interface (as I suggested at
the vendor summit), though I think we need a way to enumerate BPF taps
that aren't network interfaces (if we fix this then we can remove the
fake USB ifnets and make glebius@ happy as well).  Then you can look
at these things in wireshark (which would be a bit bizarre perhaps)

-- 
John Baldwin