linux-kernel - Re: [PATCH] mod_devicetable.h: reduce sizeof(struct of_device

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Message-ID: <62959593-6029-e66e-ebee-314db7aa6f10@metux.net>
Date:   Fri, 26 Apr 2019 13:05:57 +0200
From:   "Enrico Weigelt, metux IT consult" <lkml@...ux.net>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Darren Hart (VMware)" <dvhart@...radead.org>,
        Mattias Jacobsson <2pi@....nu>
Cc:     Jeff Mahoney <jeffm@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mod_devicetable.h: reduce sizeof(struct of_device_id) by
 80 bytes

On 25.04.19 22:31, Rasmus Villemoes wrote:

Hi,

> A typical kernel image has hundreds of static struct of_device_id
> instances (a lot of which are sentinel all-zeroes), each occupying
> ~200 bytes. Nobody initializes the .compatible member with strings
> anywhere near 128 bytes, so a lot of that memory is simply wasted.

I just wonder whether it has to be a fixed size array at all, instead
of an const char* pointer. Using a pointer should, IMHO, offer even
more savings while not having the size limit at all.

Is that struct copied as-is somewhere ?


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@...ux.net -- +49-151-27565287