Date: Sat, 13 Oct 2001 13:25:29 -0300 From: "Daniel C. Sobral" <dcs@newsguy.com> To: Vadim Vygonets <vadik-hackers@freebsd.vygo.net> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: loader.conf conditional assignment Message-ID: <3BC86AF9.BB1CF2E8@newsguy.com> References: <20011013174339.A21230@cs.huji.ac.il>
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Vadim Vygonets wrote: > > We are working on integration of network-booted FreeBSD system to > our envoronment. Naturally, different machines need different > kernels, so we pass the kernel paramater in DHCP response. > However, it gets overwritten in /boot/defaults/loader.conf. We > decided that commenting out the assignment of 'kernel' and > 'kernel_options' is not what we want, because we want both to use > the default value and to be able to override it via DHCP. > > After taking some time to learn Forth (interesting language, I > must say) and a false start (involving saving environment > variables (names and values) in a linked list and restoring them > after the assignment), I decided to use the Makefile syntax of ?= > to set an environment variable if it's not set yet, so it will be > possible to say: > > kernel?="/kernel" > > In this case, if kernel is set via DHCP, the value is not > changed, but if it's not, it becomes "/kernel". Attached is the > patch for /boot/support.4th against the version in FreeBSD 4.4. Loader.conf's syntax was designed to be such that the files could be processed by sh(1). I rather prefer to keep faithful to that by using the shell expansions tricks sh(1) has. OTOH, that wouldn't be a trivial task to undertake, and I don't have time to do it. Add to that, being able to sh-process loader.conf files is of dubious usefulness. So I do not object to such a change, as long as more people weight in first on this matter. -- Daniel C. Sobral (8-DCS) dcs@newsguy.com dcs@freebsd.org capo@the.secret.bsdconspiracy.net wow regex humor... I'm a geek To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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