linux-kernel - Re: [PATCH] Replace unnecessary perl with sed, printf, and the shell $(( )) operator.

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Date:   Mon, 16 Apr 2018 07:19:11 -0500
From:   Rob Landley <rob@...dley.net>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kstewart@...uxfoundation.org, pombredanne@...b.com,
        tglx@...utronix.de, gregkh@...uxfoundation.org,
        linux-arm-kernel@...ts.infradead.org,
        Tony Lindgren <tony@...mide.com>, Keerthy <j-keerthy@...com>
Subject: Re: [PATCH] Replace unnecessary perl with sed, printf, and the shell
 $(( )) operator.

On 04/16/2018 07:09 AM, Russell King - ARM Linux wrote:
> On Wed, Apr 11, 2018 at 08:38:37PM -0500, Rob Landley wrote:
>> You can build a kernel in a cross compiling environment that doesn't have perl
>> in the $PATH. Commit 429f7a062e3b broke that for 32 bit arm. Fix it.
...
> This looks more complicated than necessary, and therefore less readable.
> What's wrong with:
> 
> KBSS_SZ := $(shell echo $$(($$($(CROSS_COMPILE)nm $(obj)/../../../../vmlinux | \
> 		sed -n -e 's/^\([^ ]*\) B __bss_start$$/-0x\1/p' \
> 		       -e 's/^\([^ ]*\) B __bss_stop$$/+0x\1/p') ))
> 
> The sed command produces output such as:
> 
> -0xc0955e58
> +0xc10b0f9c
> 
> which the shell is then able to evaluate and produce a decimal number.
> This seems to work fine with both bash and dash.

Yes, that is better.

Acked-by: Rob Landley <rob@...dley.net>

Thanks,

Rob