Re: [PATCH tip/core/rcu 13/14] tools/memory-model/README: Expand dependency of klitmus7

Akira Yokosawa
2020-06-23T14:37:40Z

On Mon, 22 Jun 2020 17:52:30 -0700, paulmck@kernel.org wrote:
> From: Akira Yokosawa <akiyks@gmail.com>
>
> klitmus7 is independent of the memory model but depends on the
> build-target kernel release.
> It occasionally lost compatibility due to kernel API changes [1, 2, 3].
> It was remedied in a backwards-compatible manner respectively [4, 5, 6].
>
> Reflect this fact in README.
>
> [1]: b899a850431e ("compiler.h: Remove ACCESS_ONCE()")
> [2]: 0bb95f80a38f ("Makefile: Globally enable VLA warning")
> [3]: d56c0d45f0e2 ("proc: decouple proc from VFS with "struct proc_ops"")
> [4]: https://github.com/herd/herdtools7/commit/e87d7f9287d1
> ("klitmus: Use WRITE_ONCE and READ_ONCE in place of deprecated ACCESS_ONCE")
> [5]: https://github.com/herd/herdtools7/commit/a0cbb10d02be
> ("klitmus: Avoid variable length array")
> [6]: https://github.com/herd/herdtools7/commit/46b9412d3a58
> ("klitmus: Linux kernel v5.6.x compat")
>
> NOTE: [5] was ahead of herdtools7 7.53, which did not make an
> official release. Code generated by klitmus7 without [5] can still be
> built targeting Linux 4.20--5.5 if you don't care VLA warnings.
>
> Acked-by: Andrea Parri <parri.andrea@gmail.com>
> Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> tools/memory-model/README | 30 ++++++++++++++++++++++++++++--
> 1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/tools/memory-model/README b/tools/memory-model/README
> index b9c562e..90af203 100644
> --- a/tools/memory-model/README
> +++ b/tools/memory-model/README
> @@ -28,8 +28,34 @@ downloaded separately:
> See "herdtools7/INSTALL.md" for installation instructions.
>
> Note that although these tools usually provide backwards compatibility,
> -this is not absolutely guaranteed. Therefore, if a later version does
> -not work, please try using the exact version called out above.
> +this is not absolutely guaranteed.
> +
> +For example, a future version of herd7 might not work with the model
> +in this release. A compatible model will likely be made available in
> +a later release of Linux kernel.
> +
> +If you absolutely need to run the model in this particular release,
> +please try using the exact version called out above.
> +
> +klitmus7 is independent of the model provided here. It has its own
> +dependency on a target kernel release where converted code is built
> +and executed. Any change in kernel APIs essential to klitmus7 will
> +necessitate an upgrade of klitmus7.
> +
> +If you find any compatibility issues in klitmus7, please inform the
> +memory model maintainers.
> +
> +klitmus7 Compatibility Table
> +----------------------------
> +
> + ============ ==========
> + target Linux herdtools7
> + ------------ ----------
> + -- 4.18 7.48 --
> + 4.15 -- 4.19 7.49 --
> + 4.20 -- 5.5 7.54 --
> + 5.6 -- HEAD
> + ============ ==========

Paul,

I was planning to send an update on this one.
herdtoolds7 7.56 will be released later this week (now tagged 7.56-rc1).

Andrea tested klitmus7 7.56-rc1 against Linux 5.7 and 5.8-rc1.
I tested it against Linux 5.7.4.
klitmus7 worked fine in all these test.

So I think we can safely update the bottom row of the table as:

> + 5.6 -- 7.56 --

Can you amend this one directly?
Or do you want me to send a follow-up patch?

Thanks, Akira

>
>
> ==================
>