SlugOS 4.0 HEAD status update

Hi there,

This afternoon I have pushed some large changes to org.openembedded.dev.
I have checked out a clean version of the org.openembedded.dev tree  
and am testing a full build right now.

SUMMARY OF CHANGES
The kernel has been upgraded to 2.6.18. I've put in place a new build  
system that grabs patches straight from the kernel SVN repository,  
allowing NSLU2-Linux to have a single site for kernel development.

USB support, and some other drivers are now compiled as modules. This  
is to reduce the kernel image size to allow a second-stage bootloader  
to be prepended.

The open source ixp_npe driver is now enabled by default, and thanks  
to this the Intel Access Library has been jettisoned. It autoloads  
correctly on boot, allowing SSH access to the NSLU2. It has not been  
heavily tested.

For now, it is required to install the Intel NPE Microcode directly  
into the root filesystem. The ixp4xx-npe package handles this within  
the OE build environment. (Eventually, the microcode will be  
installed onto a specific location on the NSLU2 flash, so that it is  
not overwritten by kernel/rootfs changes.)

udev has been replaced by mdev, provided by busybox 1.2.1. hotplug-ng  
has been removed. This is the most controversial change made,  
partially because it will probably break turnup (not tested).

The reasons to make this change are as follows:
1) udev seems to be permanently undergoing rapid development and its  
behaviour is not consistent between versions, increasing time  
required to maintain SlugOS
2) A functioning firmware upload implementation is absolutely  
required for ethernet access
3) No distribution, however large and well resourced, seems to have a  
functioning and up-to-date udev (>94) shipping (with firmware upload  
functioning) without the use of crufty outdated hotplug/coldplug  
scripts (thinking of gentoo here). This does not bode well for our  
small and resource-limited distribution.
4) For the life of me, I can't get udev to upload microcode to the  
NPE. With mdev, a one-line config change was required, which took  
less than a minute (see the ucode_dl line in slugos/mdev.conf in the  
busybox commit).
5) mdev is fast, so booting is speeded up.
6) While mdev does not load modules automatically, this does mean  
that its behaviour is predictable, and modules can easily be loaded  
in boot scripts at appropriate times.
7) This is a matter of opinion, but I think that less hacky behaviour  
is required in my implementation of mdev - compare the mdev init  
script to the udev init script to see

The downsides of the change are:
1) People with custom udev rules will not be able to use them (Debian/ 
NSLU2 should include a full and functioning udev implementation with  
the final etch release)
2) Some script 'logic' will be required to load the right modules for  
different embedded IXP boards with different peripherals
3) USB hard disks are not currently automounted when plugged in
4) Turnup and associated boot scripts will need possibly more  
rewriting than was necessary to deal with modularisation alone

mdev documentation can be found here: http://busybox.net/downloads/ 
BusyBox.html#item_mdev
Scripts can be run automatically after a device node has been added  
or removed in order to provide functionality similar to udev

Summaries of the changes can be be seen at the links below:

busybox
http://tinyurl.com/emg2y

slugos-init
http://tinyurl.com/zt2oe

ixp4xx-npe
http://tinyurl.com/jstwb

slugos image & conf files
http://tinyurl.com/e5kd3

ixp4xx-kernel
http://tinyurl.com/pnpxe
http://tinyurl.com/zc72g

WHAT'S BROKEN
HEAD only boots correctly on the NSLU2 currently (and theoretically  
on an IXDP425).
turnup (see above and below)
Kernel does not take into account 66MHz crystal, so timer is inaccurate

TODO
Test and fix turnup (disk first, then nfs)
Add logic in slugos-init to allow different module loading for  
specific ixp4xx boards
Kernel updates (DSM-G600, loft support, new clocksource timer patches)
Specifically: Add mac definition for NAS-100D as in http:// 
tinyurl.com/ro6r3 & http://www.hohnstaedt.de/ixp_npe/readme
Copy ixp_npe branch in kernel SVN repository to trunk, and archive  
current trunk

Again, my thanks go to Christian Hohnstaedt who wrote this driver and  
has provided assistance throughout the process of integration.
http://www.hohnstaedt.de/ixp_npe/

Please reply with comments and complaints,

Michael-Luke (blaster8)
(Apparently) NSLU2-Linux.org Core Team



 
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