Re: [PATCH v4 9/9] cxl/mem: Add payload dumping for debug

[Dan Williams]

On Tue, Feb 16, 2021 at 7:50 AM Jonathan Cameron
<Jonathan.Cameron@xxxxxxxxxx> wrote:
>
> On Mon, 15 Feb 2021 17:45:38 -0800
> Ben Widawsky <ben.widawsky@xxxxxxxxx> wrote:
>
> > It's often useful in debug scenarios to see what the hardware has dumped
> > out. As it stands today, any device error will result in the payload not
> > being copied out, so there is no way to triage commands which weren't
> > expected to fail (and sometimes the payload may have that information).
> >
> > The functionality is protected by normal kernel security mechanisms as
> > well as a CONFIG option in the CXL driver.
> >
> > This was extracted from the original version of the CXL enabling patch
> > series.
> >
> > Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
>
> My gut feeling here is use a tracepoint rather than spamming the kernel
> log.  Alternatively just don't bother merging this patch - it's on the list
> now anyway so trivial for anyone doing such debug to pick it up.
>

I've long wanted to make dev_dbg() a way to declare trace-points. With
that, enabling it as a log message, or a trace-point is user policy.
The value of this is having it readily available, not digging up a
patch off the list for a debug session.