Re: [PATCH v6 5/5] selftests/mm: add UFFDIO_MOVE ioctl test

[John Hubbard]

On 12/11/23 08:32, David Hildenbrand wrote:
...
> That's an open question: do we want to be able to build selftests 
> against any host headers, and not the in-tree headers that have to be 
> manually installed and dirty the git tree?
>
> One obvious drawbacks is that we'll have to deal with all that using a 
> bunch of #ifdef, and the tests that will be built+run will depend on the 
> host headers.
>
> Especially the letter is relevant I think: Our upstream testing won't be 
> able to build+run tests that rely on new upstream features. But that's 
> what some key benefit of these selftests, and being able to run them 
> automatically on a bunch of different combinations upstream.
>
> Further, the tests are closely related to the given kernel version, they 
> are not some completely separate tests.
>
>
> Moving the the (MM?) selftests to a separate repository would make the 
> decision easier: just like in QEMU etc, we'd simply pull in a headers 
> update and only build against these archived headers.
>
> So I see the options:
>
> (1) Rely on installing the proper in-tree headers. Build will fail if
>      that is not happening.
>
> (2) Make the tests build with any host headers.
>
> (3) Regularly archive the required headers in the selftest directory
>      like external projects like QEMU do.

Or (4) Hack in little ifdef snippets, into the selftests, like we used
to do. Peter Zijlstra seems to be asking for this, if I understand his
(much) earlier comments about this.



thanks,
--
John Hubbard
NVIDIA