PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board • Hacker News Board

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#21

Post by hajile » Fri, Sep 04, 2020, 11:35 PM UTC

nsajko wrote: post #17

Why is RISC-V even so hyped up/successful? Other open ISAs precede it, and AFAIK the code density that RISC-V allows is disappointing considering the designers had an opportunity to start from scratch.

The code density beats ARMv8 (the best they could do with a fresh start do-over) and beats x86 too. They gave serious consideration to creating a compact instruction set that also doesn't cause the performance impacts seen in Thumb.

There's various reasons for a new ISA. The most appealing right now is the patent pool. Most other open ISAs are explicitly patent encumbered (recent MIPS versions) or provide zero protection (openrisc). The chances of getting sued over RISCV seem very small until you start moving to non-ISA parts of the chip.

For an ISA to succeed, the ISA itself is a distant second to the ecosystem as x86 shows so well. The amount of money an R&D being poured into RISCV would single-handedly be enough reason to adopt.

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#22

Post by neilpanchal » Fri, Sep 04, 2020, 11:41 PM UTC

PedroBatista wrote: post #13

OJFord wrote: post #11

I honestly didn't realise the Raspberry Pi isn't open source. Why isn't it? The Foundation's charitable objective is education, so sure, it's not necessary , but there really seems to be no reason for it to be closed - I suppose it's just 'closed by default'?

The Foundation doesn't make the SoCs, Broadcom does.

Also, its not possible to write your own DSI/MIPI drivers for a phone LCD that you can buy on eBay, partly for not having the DSI/MIPI specification unless you pay upwards of thousands of dollars a year and Raspberry Pi doesn't allow access to the DSI/MIPI HAL layer - its part of the SOC which Broadcom controls.

About the only way to make a device with an LCD is to use the built-in HDMI.

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#23

Post by kayfox » Fri, Sep 04, 2020, 11:41 PM UTC

inetsee wrote: post #14

OJFord wrote: post #11

I honestly didn't realise the Raspberry Pi isn't open source. Why isn't it? The Foundation's charitable objective is education, so sure, it's not necessary , but there really seems to be no reason for it to be closed - I suppose it's just 'closed by default'?

I believe it's because the Broadcom System-on-a-Chip (SOC) that the Raspberry Pi uses has one or more binary BLOBS that are required to access features on the SOC. RISC-V is an open standard; chips made based on this standard are open source.

It is possible for open source replacements for those blobs to be written, but I have not heard of any serious effort in that respect.

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#24

Post by OJFord » Fri, Sep 04, 2020, 11:44 PM UTC

PedroBatista wrote: post #13

OJFord wrote: post #11

I honestly didn't realise the Raspberry Pi isn't open source. Why isn't it? The Foundation's charitable objective is education, so sure, it's not necessary , but there really seems to be no reason for it to be closed - I suppose it's just 'closed by default'?

The Foundation doesn't make the SoCs, Broadcom does.

Ah ok - I misinterpreted the scope/emphasis.

It is open to a degree:

https://www.raspberrypi.org/documentation/hardware/raspberry...

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#25

Post by drmpeg » Fri, Sep 04, 2020, 11:45 PM UTC

simcop2387 wrote: post #9

makapuf wrote: post #7

One of the comments I made to myself was that on the die shots, USB3 part is as big as a CPU core ! What would need so much silicon ? Isn't USB3 hardware more or less a serial bus? Is it logic or memory or analog interface parts here? I am curious.

There's a great deal of communication that happens outside the operating system, and a bunch of different multiplexing modes and things like that. There's at least 4 different speeds it's going to need to talk at (1.5mbps, 12mbps, 480mbps, and 5gbps) with a good deal of synchronization and other bits. There's a rather decent amount of logic that has to be implemented, and I wouldn't be shocked if you end up needing w…

The popular Cypress/Infineon FX3 USB3 controller has a 200 MHz ARM926EJ core on chip.

https://www.cypress.com/file/140296/download

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#26

Post by ansible » Fri, Sep 04, 2020, 11:47 PM UTC

phkahler wrote: post #5

monocasa wrote: post #3

Oof, GPU by Imagination Technologies. Here's hoping their close brush with death opened them to the idea of open sourcing their code.

>> Oof, GPU by Imagination Technologies. My first thought as well. On the other hand... baby steps. We need a chip like this very much. If the first ones are slow or too proprietary that may be OK, it is still pushing the RISC-V ecosystem in the right direction. It will help validate a lot of software which will enable more open designs by having things ready to go.

I've recently purchased a Sipeed Maix Bit, which is based on the Kendryte K210 (RV64GC dual-core), just so that I can start messing around in the RISC-V 64-bit ecosystem. However, the K210 has just 8MB of on-chip RAM, limiting the applications. It ships with MicroPython, and you can run microcontroller Linux, which is a fun little hack.

However, I'm primarily interested in Rust development on the RISC-V. For bare-metal programming, the K210 is enough for me to get my feet wet. Thanks to the wonderful community, you can already run gdb for source-level debugging of Rust on that platform, with the addition of a $7 USD JTAG adapter.

That said, as long as the PicoRio board (even without a GPU) is available for less than $100 USD, I am totally buying one as soon as they are available for order.

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#27

Post by m4rtink » Fri, Sep 04, 2020, 11:48 PM UTC

OJFord wrote: post #11

I honestly didn't realise the Raspberry Pi isn't open source. Why isn't it? The Foundation's charitable objective is education, so sure, it's not necessary , but there really seems to be no reason for it to be closed - I suppose it's just 'closed by default'?

Not only is the SoC and board RPi uses open hardware, it has hardware DRM in place to prevent people using custom camera modules: https://mobile.twitter.com/marcan42/status/10884725497159188...

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#28

Post by ansible » Fri, Sep 04, 2020, 11:57 PM UTC

m4rtink wrote: post #27

OJFord wrote: post #11

I honestly didn't realise the Raspberry Pi isn't open source. Why isn't it? The Foundation's charitable objective is education, so sure, it's not necessary , but there really seems to be no reason for it to be closed - I suppose it's just 'closed by default'?

Not only is the SoC and board RPi uses open hardware, it has hardware DRM in place to prevent people using custom camera modules: https://mobile.twitter.com/marcan42/status/10884725497159188...

If you read a little further down in that thread, Eben Upton says that it is to prevent other camera vendors from just using the ISP tuning they developed for their official camera. You can still use some other camera with a CSI-compatible interface.

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#29

Post by stefan_ » Sat, Sep 05, 2020, 12:02 AM UTC

monocasa wrote: post #3

Oof, GPU by Imagination Technologies. Here's hoping their close brush with death opened them to the idea of open sourcing their code.

They managed to pick the one mobile GPU vendor that has zero open-source drivers for their chips and a reputation for horribly messy and unstable proprietary code.

Another board for the landfill, forever doomed to some 80s throwback Unix timeshare shell application.

Re: PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board

#30

Post by messe » Sat, Sep 05, 2020, 12:02 AM UTC

nsajko wrote: post #17

Why is RISC-V even so hyped up/successful? Other open ISAs precede it, and AFAIK the code density that RISC-V allows is disappointing considering the designers had an opportunity to start from scratch.

> the code density that RISC-V allows is disappointing considering the designers had an opportunity to start from scratch.

IIRC the code density beats ARMv8 and x86_64 in most situations.