Re: [PATCH] test: add fio test for device-dax

[Johannes Thumshirn <jthumshirn@suse.de>]

On Wed, Mar 29, 2017 at 05:04:31PM -0400, Jeff Moyer wrote:
> Well, the goal was to be somewhat smart about it, by not even trying to
> test things that aren't implemented or configured into the current
> kernel (such as device dax, for example).  Upon thinking about it
> further, I don't think that gets us very far.  However, that does raise
> a use case that is not distro-specific.  If you don't enable device dax,
> your test suite will still try to run those tests.  ;-)

I think I already suggested this some time ago, but again, can't we
make a syfs/debugfs/ioctl/whatever query to see what "features" are
available and check this instead of the kernel version in the test
suite? IIRC drm does similar things. Quoting from [1]:

"Have a clear way for userspace to figure out whether your new ioctl
or ioctl extension is supported on a given kernel. If you can't rely
on old kernels rejecting the new flags/modes or ioctls (since doing
that was botched in the past) then you need a driver feature flag or
revision number somewhere."

[1] http://blog.ffwll.ch/2013/11/botching-up-ioctls.html

Byte,
   Johannes

-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
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