Date: Fri, 19 Jun 2020 14:55:24 -0700 From: Enji Cooper <yaneurabeya@gmail.com> To: Kristof Provost <kp@FreeBSD.org> Cc: John-Mark Gurney <jmg@funkthat.com>, freebsd-testing@freebsd.org Subject: Re: Querying kernel features Message-ID: <0CC36359-9354-4C34-BD65-C01CB15BD5E6@gmail.com> In-Reply-To: <8B2AC268-7CA2-4FDA-BA58-FAEF7F0715BF@FreeBSD.org> References: <6C6C4F2B-CD11-4777-A97C-D249C514DEEA@FreeBSD.org> <20200618231944.GB4213@funkthat.com> <8B2AC268-7CA2-4FDA-BA58-FAEF7F0715BF@FreeBSD.org>
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> On Jun 19, 2020, at 10:47 AM, Kristof Provost <kp@FreeBSD.org> wrote: > > On 19 Jun 2020, at 1:19, John-Mark Gurney wrote: >> Kristof Provost wrote this message on Thu, Jun 18, 2020 at 22:57 +0200: >>> Say that I have a test for an optional kernel feature (say ALTQ, or >>> TMPFS) is there an elegant way of figuring out at runtime if it???s >>> available? >>> >>> Doing `sysctl kern.conftxt | grep ALTQ` feels a little inelegant, and is >>> begging for issues with incorrect matches. >>> >>> I???m tempted to add a sysctl node for ALTQ, but perhaps there???s a >>> better way. Or perhaps this should be a general feature (so we???d have >>> nodes like kernel.feature.tmpfs=1). >> >> Look at kern.features... There's a FEATURE macro to add entries to >> that, but looks like there isn't any man page for it... >> >> sys/geom/eli/g_eli.c:FEATURE(geom_eli, "GEOM crypto module"); >> > Ah, thanks, that’s pretty much exactly what I was looking for. > > There is a man page for feature_present(3), which is a C function to check for the presence of a given feature. It does the sysctl for you. > That’s not quite what I need (atf-sh make sysctl the easiest interface), but I figured I’d point out at least something is documented. There are some convenience macros in tests/freebsd_test_suite/macros.h . I’ll work on adding some atf-sh available functions for the lot (seeing as there isn’t really any good documentation for it anywhere). HTH, -Enjihelp
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