linux-kernel - Re: [PATCH 1/3] Revert "staging: mmal-vchiq: Avoid use of bool in structures"

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Message-ID: <Y3dD6Lg2L7CgkDFe@kadam>
Date:   Fri, 18 Nov 2022 11:35:52 +0300
From:   Dan Carpenter <error27@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Umang Jain <umang.jain@...asonboard.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kieran Bingham <kieran.bingham@...asonboard.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Ray Jui <rjui@...adcom.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org, linux-staging@...ts.linux.dev
Subject: Re: [PATCH 1/3] Revert "staging: mmal-vchiq: Avoid use of bool in
 structures"

On Fri, Nov 18, 2022 at 01:12:32AM +0100, Andrew Lunn wrote:
> 
> Does :1 really initialise the variable?

Obviously not.

> In "u32 enabled:1" it means
> this is a 1 bit wide bit field. It seems odd that bool is somehow
> special and :1 means something else.

If you have a bunch of consecutive bool a:1; bool b:1; then GCC will
squeeze them into the same byte.  But if you have bool a; bool b; then
they each take a byte with GCC.  I have specified GCC because the size
of bool types are a bit vague in the C standard.

regards,
dan carpenter