Re: [PATCH] xfs: add regression test for DAX mount option usage

[Dave Chinner <david@fromorbit.com>]

On Wed, Sep 13, 2017 at 05:28:39PM -0700, Dan Williams wrote:
> On Wed, Sep 13, 2017 at 4:34 PM, Dave Chinner <david@fromorbit.com> wrote:
> > /me shrugs
> >
> > I just don't like the concept of using tracepoints to as a
> > definitive diagnostic test for something working because it'll break
> > when the kernel implementation and tracepoints change. So while we
> > can probe for perf being present, we can't probe whether the
> > tracepoint we need behaves as the test expects it to...
> 
> That concern makes sense.
> 
> We handle that it a crude way in the libnvdimm unit tests by hard
> coding a required minimum kernel version and rolling a test forward to
> depend on a new kernel when assumptions about the kernel-internals
> change. The tests also inject out-of-tree kernel modules that let us
> go after specific kernel internal behavior. With this approach we
> don't end up creating userspace ABI since the test explicitly loads
> out-of-tree modules.

That's horrible. OT, but how are distros or anyone backporting
libnvdimm fixes and features supposed to test their kernels work
correctly with such a test harness?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com