On Thursday 03 November 2005 00:47, Robert Schwebel wrote:
> On Wed, Nov 02, 2005 at 09:40:24PM -0600, Rob Landley wrote:
> > > dir /dev 0755 0 0
> > > nod /dev/console 0600 0 0 c 5 1
> > > nod /dev/null 0600 0 0 c 1 3
> > > dir /root 0700 0 0
> > >
> > > and let CONFIG_INITRAMFS_SOURCE point to that file. The gpio archive is
> > > built correctly with that, but my kernel doesn't seem to use it.
> >
> > 1) You have no init in initramfs, so it goes ahead and mounts whatever
> > root= points to over it. I'm guessing that's where it's looking for
> > /dev/console from.
>
> Hmm, I thought something like that. That means that I do need a complete
> klibc based early userspace, just to get these two device nodes?
No, you just need a statically linked init program. (Which can be a shell
script using a statically linked shell. For testing purposes it can be
statically linked against glibc, it'll just be a bloated pig.)
I have a /tools directory that builds uClibc executables. (Like Linux From
Scratch Chapter 5: extract it as /tools, export PATH=/tools/bin:$PATH, and
then build software as normal.) I can post that somewhere if you'd like, or
you can extract it yourself out of my firmware linux build
(http://www.landley.net/code/firmware)...
The switch_root program in busybox is still being banged on (by me). I
haven't quite worked out what to do about /dev/console yet. I'm thinking if
it's not there, keep the one from initramfs, but haven't implemented that
tweak yet...
You also have the option of putting a single static node (console) in the /dev
directory you're going to overmount. It shouldn't hurt anything at present.
And if nothing else, it'll confirm where it's trying to get the sucker
from...
> Seems
> like I'll have to do some deeper investigation of klibc; last time I
> looked it didn't even compile for ARCH=um.
Klibc didn't, or the kernel didn't?
> > 2) What's the directory /root for?
>
> Just a relict from the default script; the first three lines should be
> enought. But it shouldn't matter.
>
> > > Is anything else needed to use an initrd, like a command line argument?
> > > My kernel boots from a nfs partition, so it sets nfsroot=...
> >
> > Note that initramfs and initrd and very different things.
>
> Is there any other known possibility to get just these two device nodes
> in an automatic way?
>From initramfs, you could try:
mount -t sysfs /sys /sys
CDEV=`cat /sys/class/tty/console`
mknod /dev/console c $(echo $CDEV | sed 's/:.*//') \
$(echo $CDEV | sed 's/.*://')
Bit of a chicken and egg problem if it refuses to run /init if it's not
already there, though. We're heading towards fully dynamic devices, but not
quite there yet...
> I'm trying to get rid of devfs, and udev works just
> fine. The only thing not solved yet is how to get the beast started
> without /dev/console and /dev/null. I don't want to create the nodes
> statically, because that's only possible with root permissions.
You don't need root access to make an initramfs configuration text file. :)
> Some background: I'm building root filesystems for embedded systems with
> PTXdist; the user is able to build the whole thing without root
> permissions; either with a cross compiler and mount it via NFS or build
> a JFFS2 image, or, with one switch, build and run it with an uml kernel.
I did something like that, only from scratch:
http://www.landley.net/code/firmware
I'll probably release version 0.8.10 later today. (Still need to make an
installer for the bootable version before I can call it 0.9...)
> I also tried ndevfs, just to get these two nodes, but I didn't find out
> how to automatically mount it on boot yet.
Presumably, either via initramfs or from init/main.c
> Robert
Rob
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