linux-kernel - Re: [Intel-xe] [PATCH 2/3] linux/bits.h: Add fixed-width GENMASK and BIT macros

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Date:   Tue, 20 Jun 2023 21:19:20 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        intel-gfx@...ts.freedesktop.org,
        Kevin Brodsky <kevin.brodsky@....com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Christian König <christian.koenig@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        intel-xe@...ts.freedesktop.org
Subject: Re: [Intel-xe] [PATCH 2/3] linux/bits.h: Add fixed-width GENMASK
 and BIT macros

On Tue, 20 Jun 2023, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> So, what does prevent you from using GENMASK_ULL()?
>
> Another point, you may teach GENMASK() to issue a warning if hi and/or lo
> bigger than BITS_PER_LONG.

What good does that do if you want the warning for a fixed size
different from unsigned long or long long? Worse, sizeof(long) depends
on arch, while the GENMASK you want depends on the use case.

> I still don't see the usefulness of that churn.

This thread is turning into a prime example of why drivers and
subsystems reinvent their own wheels instead of trying to get generally
useful stuff merged in kernel headers. :p


BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center