Date: Wed, 26 Feb 2014 14:58:20 -0800 From: Warner Losh <bsdimp@gmail.com> To: John-Mark Gurney <jmg@funkthat.com> Cc: arch@freebsd.org Subject: Re: small kernel kernel option... Message-ID: <D54F2511-57E5-4586-BAF4-9C1B7341BC87@gmail.com> In-Reply-To: <20140226222445.GD92037@funkthat.com> References: <20140226214816.GB92037@funkthat.com> <CA%2BhQ2%2BiEmvTfRd%2B7k3mZjWdDBgFqxBHnq4fj5M6=BwhaoP08Qg@mail.gmail.com> <20140226214816.GB92037@funkthat.com> <5BA6FA29-0BBE-45C1-B734-29013C5A2D29@bsdimp.com> <20140226222445.GD92037@funkthat.com>
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On Feb 26, 2014, at 2:24 PM, John-Mark Gurney <jmg@funkthat.com> wrote: > Warner Losh wrote this message on Wed, Feb 26, 2014 at 14:02 -0800: >> >> On Feb 26, 2014, at 1:48 PM, John-Mark Gurney <jmg@funkthat.com> wrote: >> >>> I'm about to commit a change to sha256 to speed it up, but the cost >>> of that speed up is an increase in code/data size from just under 1k >>> to almost 9k (as measured on amd64)... this increase is from unrolling >>> a loop.. >>> >>> Maybe we should have a global kernel option, SMALL_KERNEL, or something >>> similar that can be used to shrink code size for those that are trying >>> to build small embedded devices? >> >> I?d prefer something that?s more like OPTIMIZE_SIZE or OPTIMIZE_SPEED. > > Shall I add OPTIMIZE_SIZE and make OPTIMIZE_SPEED the default (by being > unspecified)? I don't know of a good way w/ config to make sure only > one or the other is specified (besides having some shared header #error > if they are.. and though you could say if neither is specified, balance > that optimization, but I don't see a use for it… I’d toss it into a header. No reason that config needs to error out… Warner
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