Re: User/kernelspace stuff to set/get kernel variables

[Daniel Freedman <freedman@ccmr.cornell.edu>]

On Thu, Dec 13, 2001, DevilKin wrote:
> Hello
> 
> I've been looking on the web, and couldn't really find what i would want...
> 
> Basically: is it possible to - one way or another - set variables at kernel boot and read those using userspace utilities?

Sorry, I don't know, but see below for possible solution to your problem anyway.

> for instance: i boot my kernel (using any old bootmanager that accepts kernel params)
> 
> 
> LILO: linux network=dhcp

You might want to familiarize yourself with the following kernel parameter:

"ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>"

where most options are obvious, and you'll probably want device to be
"eth0" and autoconf to be "dhcp".

HTH,

Daniel


> and later, in the init scripts, i check the value of this variable using some sort of userspace program, and if it happends to be 'dhcp' i'll invoke the dhcp client. 
> Otherwise i'd just give a static address.
> 
> I have other uses for this, for instance, you want your disks to be FSCK'ed, but don't wanna boot first, or, don't wanna go in single user mode
> 
> 
> LILO: linux dofsck=true
> 
> 
> Does something like this exist? Is it implementable in an easy way? (I know a few programming languages, but only little C(++)....)
> 
> Thanks
> 
> 
> DK
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-- 
Daniel A. Freedman
Laboratory for Atomic and Solid State Physics
Department of Physics
Cornell University