Re: [PATCH v3 2/4] generic: test mmap io fom DAX to non-DAX

Ross Zwisler
2017-04-14T15:22:34Z

On Fri, Apr 14, 2017 at 07:49:48AM -0700, Dan Williams wrote:
> On Fri, Apr 14, 2017 at 3:01 AM, Xiong Zhou <xzhou@redhat.com> wrote:
> > I agree with Ross that we don't even need ndctl and jq, if we run tests
> > on memmap setup.
>
> I don't understand this comment. How is the test determining if it is
> on an memmap defined namespace without querying sysfs?

If we we assume that a setup is *either* memmap based or NFIT based, we can
choose whether to use jq & ndctl by grepping for "memmap" with a trailing "!"
in /proc/cmdline.

If you think we need to worry about the case where users have both a valid
NFIT and a memmap kernel command line param making them a PMEM region, this
shortcut won't work.