Are you...

• ... new to NSLU2?
• ... unsure which Firmware to start with?
• ... or just want to know the differences between the NSLU2-firmware variants?

Right, here we go:

Some remarks on the various packages:

ipkg: Originally designed for the iPaq, this "lightweight package management system" is well suited to embedded linux systems like the NSLU2. The ipkg packages are the default packages for Unslung, Openslug and UcSlugC.

deb: Debian packages used for the debian distributions on the slug.

Conversion between the two packages is possible, although it's easier to install an ipkg to a .deb-based system, than the other way around. And hey, you can always try compiling from source! Detail for converting between the two package is listed here.

Some remarks on the SlugOS Variants:

SlugOS-

• lag means: SlugOS Little Endian, Arm CPU instruction set, glibc based (formerly known as DebianSlug)
• bag means: SlugOS Big Endian, Arm CPU instruction set, glibc based (aka OpenSlug)
• btu means: SlugOS Big Endian, Thumb CPU instruction set, uclibc based (aka UcSlugC)
• The package feeds for slugos-bag & openslug are currently symlinks to slugosbe. (i.e. SlugOS/BE = SlugOS-bag = OpenSlug )
• The package feeds for slugos-lag & debianslug are currently symlinks to slugosle. (i.e. SlugOS/LE = SlugOS-lag = DebianSlug )
• The package feeds for slugos-btu is currently a symlink to ucslugc. (i.e. UcSlugC = SlugOS-btu )

OpenDebianSlug, DebianSlug and GentooSlug are some sort of "pseudo" NSLU2 operating system. They're all based on some SlugOS variant. It's like having a RC-car chassis (this would be one of the SlugOS variants) where you could put some sort of car body (Debian/Gentoo) on it.

To be more precise: The NSLU2's bootloader (redboot / apex (allthough apex ) is unable to boot directly from an attached usb-storage device (like an usb-harddisk or an usb-memory stick). So instead it loads the kernel and an initial ramdisk containing a small set of tools which are used to load some additional kernel-modules and then continue to boot from the attached usb-storage device / a nfs-export / ... .
If this fails, it will continue to boot from the internal flashmemory and allows you to login via ssh to check if there are any problems.

Quote Rod Whitby from http://tech.groups.yahoo.com/group/nslu2-linux/message/20476

I often get asked to recommend a distribution for the NSLU2. Here is some objective information on each of the five different firmware distributions created or supported by the NSLU2-Linux project. In the end, it usually comes down to which applications you want to run, or which hardware you want to connect. It's not one-size-fits-all.

Unslung (through the installation of Optware packages) has about 1000 packages to choose from, each of which has been specifically compiled for the NSLU2's unique blend of capabilities. Unslung is available in big-endian mode only, and has a very old 2.4 kernel and a very old version of glibc, so support for hardware accessories is hit and miss, and there is nothing you can do to fix it if it doesn't work. Unslung has a web user interface. There is a tiny amount of room left in internal flash after installation, but Unslung is meant to be run from an external storage device. If the external device fails, Unslung falls back to running from internal flash.

SlugOS has about 5000 packages to choose from - 4000 from OpenEmbedded, which have been specifically compiled mainly for handheld, limited memory devices, and 1000 from Optware (as per Unslung). SlugOS is available in either big-endian or little-endian modes, and uses a 2.6.21.7 kernel and a recent version of glibc. SlugOS does not have a web user interface. There is a small amount of room left in internal flash after installation (enough to run some small server applications), but installation of large packages will require an external storage device. If the external device fails, SlugOS falls back to running from internal flash.

Angstrom has the same 4000 OpenEmbedded packages, but is built using the EABI version of the ARM application binary interface, and therefore has much better floating point performance than any other distro for the slug. Angstrom is available in either big-endian or little-endian modes, and uses a 2.6.21.7 kernel and a recent version of glibc. Angstrom does not have a web user interface as such, but some packages are available that provide web interfaces to some applications. There is a small amount of room left in internal flash after installation (enough to run some small server applications), but installation of large packages will require an external storage device. If the external device fails, then either a reflash or a serial console is currently required for recovery.

Debian has well over 10000 packages, but they have been compiled for desktop systems, and are therefore not optimised for the small-memory NSLU2. Debian is available in little-endian mode only, and uses a 2.6.18 kernel and a recent version of glibc. Debian has some packages that provide web-based interfaces. Debian can only run from an external storage device (which means that there is no recovery ability other than a reflash if that external device stops working).

OpenWrt has just under 2000 packages to choose from - about 1000 from Optware, and about 1000 from OpenWrt. OpenWrt is available in big-endian mode only, and uses a 2.6.21.6 kernel and uClibc. If you want to do wireless or sophisticated routing, then you can't go past OpenWrt. It is also the only 2.6 kernel distro for the slug which has a web user interface (X-Wrt) included in the installation image. OpenWrt has a significant amount of internal flash left after installation (since uClibc uses so much less space than glibc), so it is very good for disk-less applications. You can also run it from an external storage device if you choose. If the external device fails, then either a reflash or a serial console is currently required for recovery.