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Message-ID: <2f1603fa-d03c-412c-895c-bc4afa06834b@intel.com>
Date: Thu, 30 May 2024 10:54:34 -0700
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] ethernet: octeontx2: avoid linking objects into multiple
 modules
To: Arnd Bergmann <arnd@kernel.org>, Sunil Goutham <sgoutham@marvell.com>,
	Geetha sowjanya <gakula@marvell.com>, Subbaraya Sundeep
	<sbhatta@marvell.com>, hariprasad <hkelam@marvell.com>
CC: Arnd Bergmann <arnd@arndb.de>, "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, "Paolo
 Abeni" <pabeni@redhat.com>, Richard Cochran <richardcochran@gmail.com>, Suman
 Ghosh <sumang@marvell.com>, Simon Horman <horms@kernel.org>, "Tony Nguyen"
	<anthony.l.nguyen@intel.com>, Jiri Pirko <jiri@resnulli.us>, "Mateusz
 Polchlopek" <mateusz.polchlopek@intel.com>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
References: <20240528152527.2148092-1-arnd@kernel.org>
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From: Jacob Keller <jacob.e.keller@intel.com>
In-Reply-To: <20240528152527.2148092-1-arnd@kernel.org>
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On 5/28/2024 8:25 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Each object file contains information about which module it gets linked
> into, so linking the same file into multiple modules now causes a warning:
> 
> scripts/Makefile.build:254: drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_devlink.o is added to multiple modules: rvu_nicpf rvu_nicvf
> 

When I tried to build, I don't see any warnings produced on the current
net-next with W=1. Is this something new and not yet in net-next tree?
If not, how do I enable this warning in my local build?

> Change the way that octeontx2 ethernet is built by moving the common
> file into a separate module with exported symbols instead.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---

The change makes sense to me. I built and tested both before and after
this change.

On my system, before the build change, the driver built to 3 separate
modules totaling 2029176 bytes:

> -rw-r--r--. 1 jekeller jekeller   72104 May 30 10:46 otx2_ptp.ko
> -rw-r--r--. 1 jekeller jekeller 1774008 May 30 10:46 rvu_nicpf.ko
> -rw-r--r--. 1 jekeller jekeller  183064 May 30 10:46 rvu_nicvf.ko
After this change, the driver builds to 5 separate modules totaling
1977984 bytes:

> -rw-r--r--. 1 jekeller jekeller   81480 May 30 10:46 otx2_dcbnl.ko
> -rw-r--r--. 1 jekeller jekeller   19784 May 30 10:46 otx2_devlink.ko
> -rw-r--r--. 1 jekeller jekeller   72104 May 30 10:46 otx2_ptp.ko
> -rw-r--r--. 1 jekeller jekeller 1698880 May 30 10:46 rvu_nicpf.ko
> -rw-r--r--. 1 jekeller jekeller  105736 May 30 10:46 rvu_nicvf.ko

This is a savings of 51192 bytes from removing the duplicated object code.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>