Yet another potential RISC OS target?

Just throwing this up for discussion …

http://tinyurl.com/3fzbjxo

http://www.raspberrypi.org/

Nice one, Rik – wow! It’d be great if this were to be ready for sale at BETT 2012! Does anyone have access to a GeeksPhone One or similar open source ARMv6 device? I’ve read somewhere on this forum references to ARMv7 along with ARMv6+ so does that mean there’s plenty of common ground? I wonder which specific processor¹ Raspberry Pi are using. What are the drawbacks of spending time looking into this?

¹ [Edit: I guess I meant SoC!]

I’ve read somewhere on this forum references to ARMv7 along with ARMv6+ so does that mean there’s plenty of common ground?

The ‘Cortex’ branch of the kernel that we’re using for the OMAP port should work on any CPU from ARMv3 to ARMv7 (apart from multi-core ones and Thumb-only ones), and all the work that’s being done to fix ARMv7 incompatabilities is equally applicable to ARMv6. So there’s not much to worry about in terms of CPU incompatabilities.

I wonder which specific processor Raspberry Pi are using. What are the drawbacks of spending time looking into this?

No drawbacks I can think of. The Raspberry Pi website lists it as being an ARM11, so we know it’ll be ARMv6, and there’s the possibility of VFPv2. But we’d need to find out which SoC they’re using, so we know how difficult it’ll be to get hold of all the hardware docs.

They are aiming at education and RISC OS has a big history there.

I’ll volunteer to try and get some technical docs from Raspbery Pi, if that’s acceptable. If there are any pertinent questions I should ask, let me know.

Yeah, that’s fine.

Obvious questions I can think of:

• What SoC they’re using
• Whether they’d be able to give us the schematic/circuit diagram for the board (Perhaps mentioning that it’s so that we can work out how to drive everything, not to create our own clone! Although since they’re a charity I guess they won’t be as paranoid as a commercial company would be)
• Whether there’s a serial or JTAG header which we could use for debugging (It looks like they’ve got something connected up in those photos, so I’d assume that they’d at least leave the solder pads there in the final design)

Ok, I’ve sent an introductory email to Raspberry Pi, not mentioning technical details but testing the waters so to speak. I’ll report back when they reply.

I had a 5 minute chat with one of the trustees this evening before I’d seen this thread (who happens to work down the corridor from me). Since it’s been on Slashdot they’ve been utterly deluged with mail – one every few seconds or something. So you might not get a reply, but if you have specific points I’ll see what I can find out. At the moment I know some stuff but I don’t know what’s public and what isn’t. You might also wish to read this:
http://tech.slashdot.org/comments.pl?sid=2131414&cid=36047430

SoC vendor I probably shouldn’t say until I know it’s public, but I think it’s (semi-)custom. Suffice it to say I don’t believe RISC OS has run on that vendor’s parts before. You can probably work out the SoC vendor if you look at the names of trustees:
http://www.charity-commission.gov.uk/Showcharity/RegisterOfCharities/ContactAndTrustees.aspx?RegisteredCharityNumber=1129409&SubsidiaryNumber=0

Release of schematic is something that depends on the business model, which I’m not clear on. People will be pushing for it, so I would assume those arguments are already being made. Similarly arguments will be being made regarding hardware docs, though it depends on how protective the SoC vendor is (if I look on their website for a product from what I believe is the same group, there’s very little detail given). Again there will be people pushing for it (the SoC vendor is onboard the project).

I think it’s fair to assume there will be access to JTAG or similar, subject to space constraints. (I don’t actually know any facts on this point, but it would be unusual not to provide such functionality). Though whether there’s enough space to have a header rather than arbitrary solder pads I don’t know.

We’ll have some boards to play with at some point, so I’ll see if I can borrow one to demo sometime…

I got a reply from Raspberry Pi, which given the volume of enquiries they must have had is encouraging. To summarise:

Yes, we’ll definitely support porting other OSs, though for the first little while it may be a case of reading our Linux kernel sources for pointers about the hardware.

I’m on the mailing list so I’ll post updates here as I get them.

Hi all
Can you give me an idea of what you’d need in the way of help to get RISC OS going on the Raspberry Pi device? No promises of support, but it would be a neat thing to have as an OS option.

Cheers
Eben Upton
Director, Raspberry Pi Foundation

Can you give me an idea of what you’d need in the way of help to get RISC OS going on the Raspberry Pi device? No promises of support, but it would be a neat thing to have as an OS option.

The primary thing would be technical documentation for the SoC. Licensing restrictions mean that we can’t include GPL code in the RISC OS ROM image. So we’ve either got to write our own hardware drivers or take drivers from somewhere with more permissive licensing (e.g. the BSD license is fine).

Other than that we could do with a schematic/circuit diagram of the board (in case we need to worry about things external to the SoC, e.g. GPIO assignment), and confirumation as to whether there’ll be any kind of debugging interface (I can see something that looks like either a serial or JTAG header in the photos on your website. So as long as the header or the solder pads are left there on the finished board, that should be all we need for debugging during the initial bring-up phase).

Isn’t there also talk of a Wi-Fi option for the Raspberry Pi? If so, then getting that working with RISC OS would be a welcome bonus. While many schools may not currently have Wi-Fi, it’s not completely unheard of (especially if the head uses a smartphone, I guess).

Has ROOL requested/ordered an alpha board, as an external developer? If there could be a RISC OS port at launch, that’d be great.

Additionally, the read/write SD card facility could be critical for early adoption by teachers, as "By default, storage is on the SD card that contains the GPU firmware, kernel image and rootfs."

I’ve emailled a request about becoming a developer.

Okay, thanks – that’s useful feedback. I guess the most interesting issue will be the USB controller. It’s a Synopsys USB 2.0 OTG core with (I believe) a GPL driver of substantial size and fiddliness. I wouldn’t want to try to write a driver for it from the ground up. I mentioned to Rik that I can put you guys at the head of the queue for production devices later in the year (alpha boards are probably in too short supply).

Cheers
Eben

Thanks for joining the discussion here, Eben!

I’m quite exicited by this prospect, I think the Raspberry Pi device looks cool. When the time comes, I’ll contribute to a bounty to buy development boards.

Yes, I too think this is exciting.
I’ve placed on linked headline on the RISCOScode website.
It’d be great if RISC OS could ride the ‘crest of the wave’ that’s
going to surround the launch of Raspberry PI.
It’s bound to be national news.
If RISCOScode can help in any way, give us a shout.
Regards,
Martin.

http://www.RISCOScode.com

headline on the RISCOScode website

…with the link to TransferSummit in Oxford next week, where Raspberry Pi will be present. Does anyone local and with some free time fancy trying to get a press pass (perhaps via Archive)?

With the SoC in question becoming public knowledge, I have a confession. I work at Broadcom alongside Eben and am responsible for part of the BCM2835 silicon and associated firmware. I’m just starting to look at the feasibility of porting RISC OS to it, and Aemulor in due course. It’s something we’re keen to see happen so I should have no problems with support.

Cool – thanks for sharing that news! IMHO it’d be wonderful to have some educational software and programming examples running on the Raspberry Pi under RISC OS at the BETT show.

These devices seem to be quite interesting: Omap4 at 1,5GHz, so a single core might already allow for a lot of speedup, + Hard Disk 250GB and USB Host (at least one for the UMTS dongle):
http://www.archos.com/products/gen9/index.html

I recall that someone tried the current ROM with the OMAP4 – but not what was the result…

I am trying to follow the news from IFA – a lot of tablets are announced with OMAP (Archos, Samsung, Toshiba…), which should be a good thing for RISC OS after all those Tegra2 devices. There are some interesting reports at armdevices.net.

Sounds exciting – especially since I rather have a new complete hardware and not just a bare board though one allowing me to add a bigger screen and keyboard and one running Impression Publisher (native or with Aemulor).

I recall that someone tried the current ROM with the OMAP4

"Not to be out-sneaked, Willi Theiss […]"

news from IFA

At tabletblog.de? (Also, here’s a roundup in English for the non German speakers.)

I got the information from the german cT magazine, they had a IFA article…