There are some interesting points of comparing experience between Open firmware and LinuxBIOS so I am copying the list.
Tarl Neustaedter Tarl.Neustaedter@sun.com writes:
Eric W. Biederman wrote:
Tarl Neustaedter Tarl.Neustaedter@sun.com writes:
If you have any specific questions about OpenFirmware, I'd be delighted to provide assistance. I've been doing IEEE 1275 since 1996, and was at one time a voting member of that committee (since pretty much defunct). The specs are engraved upon my skull by now.
Cool. Stefan Reinauer stepan@suse.de is more likely to ask questions as he is the primary implementor of OpenBIOS. Which is a payload from the LinuxBIOS context. As a standard for running code in options roms it does not look too bad.
The main problem is that cards don't usually come with IEEE 1275 FCode on them. We've pretty much had to write all of ours, and have gotten tired of it - we're actually looking at LinuxBIOS as a way to get out of that business, and just build in the drivers we care to in the Linux kernel on the prom. But I can answer questions any questions about writing FCode, it's most of what I've done in recent years.
Interesting. The observation that powerful firmware eventually becomes an OS so you might as well use an OS, seems true :)
The one problem with using Linux so far has been size constraints. The primary interim solution has been to use etherboot. You have to port the Linux drivers to it but it close enough you don't have to rewrite them from scratch, and it is small. 16K-32K is typical with one network driver and a IP stack. 128K when you build in all the network drivers.
I have recently found some kernel patches that start to shrink the Linux kernel by allowing you to compile out unnecessary pieces so I about ready to make a foray into using Linux as our bootloader again. But until I have squeezed a lot of the size bloat out I won't be convinced it is the way to go.
The location where option roms come into play in the pc world are scsi adapters, raid controllers, and video. For scsi adapters and raid controllers every case I have looked at the linux drivers are good enough that you don't need the option roms. Video drivers are still problematic.
How has sun coped with getting video drivers for high end video cards. I know Apple seems to have succeeded in working with NVIDIA. I suspect that is with open firmware side but I don't know.
Eric