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Subject: Re: [PATCH tip/core/rcu 13/14] tools/memory-model/README: Expand
 dependency of klitmus7
To:     paulmck@kernel.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org
Cc:     stern@rowland.harvard.edu, parri.andrea@gmail.com, will@kernel.org,
        peterz@infradead.org, boqun.feng@gmail.com, npiggin@gmail.com,
        dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr,
        Akira Yokosawa <akiyks@gmail.com>
References: <20200623005152.GA27459@paulmck-ThinkPad-P72>
 <20200623005231.27712-13-paulmck@kernel.org>
From:   Akira Yokosawa <akiyks@gmail.com>
Message-ID: <e3693dec-213a-3f65-eb1c-284bf8ca6e13@gmail.com>
Date:   Tue, 23 Jun 2020 23:37:32 +0900
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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

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