linux-kernel - Re: [PATCH 1/2] bitmap_parse: support 'all' semantics

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Message-ID: <20210421111932.36665920@gandalf.local.home>
Date:   Wed, 21 Apr 2021 11:19:32 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Yury Norov <yury.norov@...il.com>
Cc:     linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
        linux-doc@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Jonathan Corbet <corbet@....net>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH 1/2] bitmap_parse: support 'all' semantics

On Tue, 20 Apr 2021 20:13:25 -0700
Yury Norov <yury.norov@...il.com> wrote:

> @@ -76,6 +76,11 @@ to change, such as less cores in the CPU list, then N and any ranges using N
>  will also change.  Use the same on a small 4 core system, and "16-N" becomes
>  "16-3" and now the same boot input will be flagged as invalid (start > end).
>  
> +The special case-tolerant group name "all" has a meaning of selecting all CPUs,
> +such that "isolcpus=all" is the equivalent of "isolcpus=0-N".

I'm OK with the concept of this patch set, but really? That is a horrible
example. One should NEVER set isolcpus to all!

-- Steve


> +
> +The semantics of "N" and "all" is supported on a level of bitmaps and holds for
> +all users of bitmap_parse().
>