Date: Mon, 12 Jan 2009 07:36:20 -0800 From: Andrew Thompson <thompsa@FreeBSD.org> To: Andrew Brampton <brampton@gmail.com> Cc: hackers@freebsd.org Subject: Re: Determine if a kernel is built with a specific option? Message-ID: <20090112153620.GA76347@citylink.fud.org.nz> In-Reply-To: <d41814900901120355h780a3232u14fa1e5da8f280ad@mail.gmail.com> References: <d41814900901120355h780a3232u14fa1e5da8f280ad@mail.gmail.com>
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On Mon, Jan 12, 2009 at 11:55:11AM +0000, Andrew Brampton wrote: > Hi, > I was wondering how a autoconf configure script can determine if the > kernel is built with a particular option. In this case the code I have > can make use of the FreeBSD polling driver, which by default isn't > built into a kernel. So I want my configure script to determine if the > kernel supports it, if so sets a #define, otherwise doesn't. > > In the past I have basically hacked my way though these configure > scripts by looking at other examples. One such example I found was for > Linux, which does something like this: > > AC_CACHE_CHECK(for device polling kernel extension, ac_cv_linux_poll_extension, > [if grep polling `find_linuxpath include/linux/netdevice.h` >/dev/null > 2>&1; then > ac_cv_linux_poll_extension=yes > else ac_cv_linux_poll_extension=no; fi]) > if test $ac_cv_linux_poll_extension = yes; then > AC_DEFINE(HAVE_LINUX_POLLING) > fi > > So I simply want to figure out an equalavant check I can do on FreeBSD. I believe the correct way is to read kern.features from sysctl and the appropriate code marks it with FEATURE(name, "description"); Having said that the polling code does not set this so would need to be added. Andrew
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