Mitch Bradley wrote: I don't think I can arrange it, but I know I'm going to be asked where (i.e. what country) your doorstep is :-) -- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues]

On 6/25/2013 2:22 PM, James Cameron wrote: http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Periphera… describes the peripherals. The mini UART looks pretty much like the 16550 (PC COM port) UART that everybody seems to use as a programming model these days, so no drama there. The EMMC controller looks like the common SDHCI programming model. Same old same old. The USB controller uses Synopsis IP; it seems like you can get the manual if you register. The Ethernet is on USB - it's inside an SMSC LAN9512 integrated USB hub/ethernet chip. I don't know its details, but in the past, adding OFW support for new USB ethernet interfaces has not proven to be difficult.

James Cameron wrote: I think the problem here is that for OpenFirmware to really be useful, i.e. to the same extent that it is on Sun systems, it needs to take control as early as possible and in particular shouldn't be loaded from a filesystem which can be screwed. On a Raspberry Pi, that raises two issues: i) The (originally undocumented) Broadcom SoC contains firmware or equivalent hardware to pull a first-stage loader off the SD card. So the SD card is always needed, even though the mechanical connector is known to be one of the less-reliable components and the card itself will, ultimately, have a limited life. ii) If one grits ones teeth and subverts that mechanism, one ends up in control of the SoC rather than in control of the application processer that normally runs Linux. If one instead tolerates the existing multi-stage loader, then one should be able to boot Forth onto the application processor in lieu of Linux. But this breaks the Sun model of "Open Boot in ROM, everything else on disc", and loses the desirable characteristic that any media or controller problem returns you to the "ok" prompt with diagnostic capabilities, and as such I'm not sure it's worth the effort. I'd be interested to know of any low-cost boards which could have OpenFirmware grafted in sufficiently early. A colleague is trying to build some router systems which, as a prerequisite, must have a serial console port. -- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues]

James Cameron wrote: One of the interesting features of OBP/OpenFirmware is the extent that it allows you to explore partition tables etc. so that you can see why things are going wrong. That sort of thing really is valuable for headless systems, I struggled with Slugs as routers for a while and not having a decent console really was a pain. -- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues]

Mitch Bradley wrote: I agree, but the only mention I see of the combination turns out to be limited to DeviceTree. Another alternative would obviously be one of the resurgent MIPS boards. -- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues]