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Date:   Mon, 30 May 2022 17:56:06 +0100
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Jani Nikula <jani.nikula@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
        Viresh Kumar <vireshk@kernel.org>,
        Shiraz Hashim <shiraz.linux.kernel@gmail.com>,
        Ville =?iso-8859-1?Q?Syrj=E4l=E4?= 
        <ville.syrjala@linux.intel.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
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        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        SoC Team <soc@kernel.org>
Subject: Re: mainline build failure due to f1e4c916f97f ("drm/edid: add EDID
 block count and size helpers")
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On Mon, May 30, 2022 at 03:35:28PM +0200, Arnd Bergmann wrote:
> The annotations for edid are completely correct and necessary. However
> other driver authors just slap __packed annotations on any structure
> even if the layout is not fixed at all like:
> 
> struct my_driver_priv {
>        struct device dev;
>        u8 causes_misalignment;
>        spinlock_t lock;
>        atomic_t counter;
> } __packed; /* this annotation is harmful because it breaks the atomics */
> 
> or if the annotation does not change the layout like
> 
> struct my_dma_descriptor {
>      __le64 address;
>      __le64 length;
> } __packed; /* does not change layout but makes access slow on some
> architectures */

Sounds like we need a howto document for people to ignore and continue
doing their own thing. :P

-- 
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