From owner-freebsd-hackers Wed Nov 6 3:57:29 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C0D0737B401; Wed, 6 Nov 2002 03:57:28 -0800 (PST) Received: from gull.mail.pas.earthlink.net (gull.mail.pas.earthlink.net [207.217.120.84]) by mx1.FreeBSD.org (Postfix) with ESMTP id 77A8243E4A; Wed, 6 Nov 2002 03:57:28 -0800 (PST) (envelope-from tlambert2@mindspring.com) Received: from pool0009.cvx22-bradley.dialup.earthlink.net ([209.179.198.9] helo=mindspring.com) by gull.mail.pas.earthlink.net with esmtp (Exim 3.33 #1) id 189OoJ-00069j-00; Wed, 06 Nov 2002 03:57:27 -0800 Message-ID: <3DC9035A.3DFCF3BB@mindspring.com> Date: Wed, 06 Nov 2002 03:56:10 -0800 From: Terry Lambert X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Maxime Henrion Cc: "M. Warner Losh" , chuck_tuffli@agilent.com, freebsd-hackers@FreeBSD.ORG Subject: Re: load time module parameters? References: <20021105222958.GH17013@cre85086tuf.rose.agilent.com> <20021105.222147.10576668.imp@bsdimp.com> <20021106104421.GK26605@elvis.mu.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Maxime Henrion wrote: > With kenv(1) you can modify kernel environment variables, which hold the > tunables. Previously, you could only set those at boot time. Note that there are some values which are used to determine the size of KVA space allocations, and changing them after boot, even if it's permitted, will have no real effect. For example, you can change the value of "maxfiles" with a sysctl, but doing so will not increase the number of simultaneous network connections your system will support, since the reserved space for tcpcb's and sockets is not increased. The kernel environment is most useful for diagnostic porposes, and for use in the way descrived in this thread -- to provide a means of passing parameters that should not be parameters to modules that should not need parameters in the first place. Many times, hacking the values post-boot will have little or no effect. It's too bad the things that will have no effect were exported as writeable, instead of resulting in an error. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message