Subject: Re: CF mounted on wd0
To: Simon Burge <>
From: Marcin Jessa <>
List: tech-embed
Date: 06/27/2005 15:53:52
On Mon, 27 Jun 2005 23:42:56 +1000
Simon Burge <> wrote:

> On Mon, Jun 27, 2005 at 03:24:48PM +0200, Marcin Jessa wrote:
> > Hi guys.
> > 
> > Normally creating a small NetBSD build with rootfs inserted into kernel you mount the roofs as memory file system, e.g.
> > /dev/md0a       /               ffs     rw,-s=32768     1 1
> > 
> > with following kernel options:
> > options         MEMORY_DISK_HOOKS
> > options         MEMORY_DISK_IS_ROOT     # force root on memory disk
> > options         MEMORY_DISK_SERVER=0    # no userspace memory disk support
> > options         MEMORY_RBFLAGS=0        # don't force single user
> Look at options(4) for MEMORY_DISK_IS_ROOT:
>      options MEMORY_DISK_IS_ROOT
>      Forces the md(4) RAM disk to be the root device.  This can only be over-
>      ridden when the kernel is booted in the 'ask-for-root' mode.
> Leaving out that option should allow you to then use your CF as the root
> device.
> Also, do you really want to leave the memory disk in if you are using CF
> on root?  I'd guess that you probably don't want any of the memory disk
> options.  That's just burning a chunk of RAM otherwise...

Yes, I want the rootfs not to be using memory of my devices and rather store all the configs on the CF.
The rootfs will be mounted ro on the CF and never change/get written to, except for system upgrades.
I will mount /tmp as a rw memory file system instead and create a couple of symlinks for applications that need write to the CF, like dhclient etc.
All the memory avaliable on the device can then be used to run the applications instead.

I've been running devices with md0 mounted / but that makes no sense having a robust rw device like CF.