Date: Tue, 19 Sep 2006 08:43:53 -0600 (MDT) From: Warner Losh <imp@bsdimp.com> To: freebsd-drivers@freebsd.org, gireesh.nagabhushana@neterion.com, olli@lurza.secnetix.de Subject: Re: Reading configuration file from driver during load Message-ID: <20060919.084353.41650344.imp@bsdimp.com> In-Reply-To: <200609191346.k8JDk9b3076219@lurza.secnetix.de> References: <6387977.post@talk.nabble.com> <200609191346.k8JDk9b3076219@lurza.secnetix.de>
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From: Oliver Fromme <olli@lurza.secnetix.de>
Subject: Re: Reading configuration file from driver during load
Date: Tue, 19 Sep 2006 15:46:09 +0200 (CEST)
> Gireesh wrote:
> > I have a driver which has some parameters hardcoded as of now. It requires
> > values of these parameters to be available during load (during attach
> > function). My requirement is to read these parameters from a configuration
> > file so that we can load driver with different values to parameters without
> > rebuilding driver.
>
> I think that sysctl or kenv variables are best suited for
> that purpose. There are a lot of examples for that in
> existing drivers.
The 'kenv' variables are best wrapped in the tunable interfaces. For
example:
u_long cbb_start_16_io = CBB_START_16_IO;
TUNABLE_ULONG("hw.cbb.start_16_io", &cbb_start_16_io);
SYSCTL_ULONG(_hw_cbb, OID_AUTO, start_16_io, CTLFLAG_RW,
&cbb_start_16_io, CBB_START_16_IO,
"Starting ioport for 16-bit cards");
This is from the cbb driver. It is a hint/tunable that can also set
the starting I/O port address range to use for 16-bit cards. Users
can either place the following line in /boot/loader.conf or in
/etc/sysctl.conf.
hw.cbb.start_16_io=0x300
The former sets it at attach time, while the latter sets it early in
the boot process, but after it has attached. You can also set it at
run-time:
sysctl hw.cbb.start_16_io=0x300
Warner
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