Date: Thu, 28 Feb 2019 01:39:51 +0000 From: "Bjoern A. Zeeb" <bz@FreeBSD.org> To: "Rick Macklem" <rmacklem@uoguelph.ca> Cc: "FreeBSD Net" <freebsd-net@freebsd.org>, rgrimes@freebsd.org Subject: Re: use of #ifdef INET and #ifdef INET6 in the kernel sources Message-ID: <8EDE90B3-0C33-47B5-88D8-964B131AEE2E@FreeBSD.org> In-Reply-To: <QB1PR01MB353721C2A0CA0E38C7A8571EDD750@QB1PR01MB3537.CANPRD01.PROD.OUTLOOK.COM> References: <QB1PR01MB353721C2A0CA0E38C7A8571EDD750@QB1PR01MB3537.CANPRD01.PROD.OUTLOOK.COM>
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On 28 Feb 2019, at 1:11, Rick Macklem wrote:
> I thought (can't remember when/how I was told) that it was no longer
> recommended to add
> #ifdef INET
> or
> #ifdef INET6
> to the kernel sources.
Not sure who said this.
> I'll admit I think #ifdef'ng code when it isn't necessary to get it to
> build makes the
> code less readable and, as such, I prefer not to do this.
We all agree on this.
> So, is this still recommended for blocks of code that only execute for
> the version
> of IP, but will build for kernels that do not have the particular
> "options INET{6}"
> in the kernel config?
Yes.
> If it is still recommended, I will do it, but I'll admit I don't
> understand why it should
> be done? (All it does is reduce the size of the executable by a small
> amount and
> that doesn't seem significant to me.)
That small amount is still relevant on some devices where people go to
great lengths to fit our constantly growing base into a tiny small
thingy.
And it allows you to lose code from your kernel that you don’t
need/want, such as if you’d want to rip out all INET sources from a
tree.
I know both of these groups still do exist.
Also every code not compiled in is not an attack surface, where you
think it’s executed or not.
/bz
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