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All I've ever heard about Raspberry Pi is that its an "open source" SoC. But I see that the CPU inside the BroadCom SoC is an ARM chip.

My understanding of open source hardware is that every single hardware component on it has to be open source in order for the unit as a whole to be OSH. But if ARM is proprietary, then how can RPi be OSH?!?

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    As Recantha points out, it isn't open source hardware. It uses predominantly open source software because that's the easiest way to get anything done for something like this.
    – goldilocks
    Jan 21, 2015 at 18:59
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    Eben Upton has pointed out that the engineering focus on the RPi is on cost, not on being openness.
    – cspirou
    Feb 4, 2015 at 9:28
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    Raspberry Pi is not opensource software or hardware. Nothing about it is.
    – Denis
    Feb 16, 2020 at 13:36

4 Answers 4

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Raspberry Pi has never maintained that the Pi is open source. There are many parts of it, especially the software, which are open source, but not everything is. There has been criticism of the Pi for having parts which are closed source, however given that the aim of the Pi is education of children, open sourcing everything is not seen as a priority.

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    Especially the early bootloader is not open source software. Do note that the 0-th stage bootloader is actually GPU firmware ... the system grew that way
    – flakeshake
    May 30, 2016 at 8:22
  • I beg to differ. I feel "The Foundation" has played up the open-source aspects of its device. The hardware & firmware are closed-source. Only the Linux OS is open & its GPL license requires modifications made to it also be open-source. Claiming their "aim" is education of children borders on preposterous. Computing education requires more than software education - It also requires hardware & firmware education. They say one thing, and do something different. And as a "charity": approx 23% of Foundation expenses are "charitable"
    – Seamus
    Jun 15, 2021 at 23:42
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Not sure where you got the impression that the Pi (or anything else for that matter) is 'open source HARDWARE' ..

For sure it's not .. it does however run Open Source Software on a SOC that includes a GPU with micro-code which is a closed source 'blob' (it has to be for two very good reasons - (1) you can perform H264, MPEG and VC1 video decode on the GPU (and that means a Licence Fee is REQUIRED to stay legal) and (2) the GPU silicon is an ancient design with a number of 'undocumented features' (so anyone changing the micro-code for one function risks 'breaking' it's operation in other, apparently unrelated, functions)

Whilst I would agree that not having access to the GPU microcode is a bit of a drawback, especially for anyone wanting to achieve any sort of real performance out of the Pi, it was never really aimed at anything other than School kids (apparently the 'hobbiest' came as a bit of an afterthought ..)

On the other hand, where else can you get so much 'free' software (and so much 'free' support) on a system for less than $30 ?

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  • "or anything else for that matter" -> There is open source hardware; the example closest to the pi would be the BeagleBoard. It's pretty rare though, especially in the PC/laptop realm. Note the FOSS software you refer to actually runs on anything, has been evolving for decades, and was not designed especially for the pi -- it was just sort of re-branded. I believe the Rpi Foundation doesn't care one way or another about open design except in so far as it is convenient for them.
    – goldilocks
    Mar 12, 2015 at 10:44
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    "Open Source Software on a SOC that includes a GPU with micro-code which is a closed source 'blob'" Which basically makes it even on software-level closed source. There needs to be only a single software component in a system to be closed source in order to make the whole system closed source. Also the additional for some valuable for others unnecessary software that is preinstalled on the larger Raspbian image (since Jessie we have Lite and non-lite version) has some pretty solid closed source applications. May 9, 2016 at 10:14
  • I believe the fact that the SoC bootloader is closed source doesn't change much, as the memory is One-Time-Programmable anyway.
    – jiggunjer
    Jan 25, 2017 at 4:52
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Here is an essential update now, as of January 2021. Raspberry Pi Foundation came up with "Raspberry Pi Pico" which is most open source:

Unlike the mostly open source, Broadcom based Raspberry Pi boards, the Raspberry Pi Pico is fully open source, with schematics and design files already posted. The exhaustively documented RP2040 chip is also far more open than any Broadcom processor. linuxgizmos.com

By the way, used in the board chip RP2040 custom designed by Raspberry Pi.

Update (June 2021):

Raspberry Pi's new RP2040 chip is now on sale–for just $1

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  • In addition, Arduino and Adafruit adapted the chip and created Arduino Nano RP2040 Connect link, Adafruit ItsyBitsy RP2040 link, and Adafruit Feather RP2040 link
    – Qareke
    Jan 28, 2021 at 20:56
  • The RP2040 uses ARM Cortex-M0+ cores. Is this chip all open source as you said, or just more open as your quote stated? Is a there a gate-level description of the processor, for example? Jan 28, 2021 at 22:20
  • I clarified my post. The board is open source, chip is "far more open" as quote says. Here is RP2040 Datasheet, Using RP2040 to build Boards
    – Qareke
    Jan 29, 2021 at 3:22
  • @ngm_code Seems they don't attribute to any license framework, just say: "These design files are made available openly, with no limitations. Permission to use, copy, modify, and/or distribute this design for any purpose with or without fee is hereby granted." Also design, board, BOM can be found here:zip download
    – Qareke
    Jan 29, 2021 at 3:43
  • "Far more open" is not far enough. Give me Verilog or a cycle accurate sim for the (very interesting) PIO block, and then we'll talk. Jan 24 at 19:35
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There are many different open source licenses out there. With each license, the definition of open source can be quite different with regard what needs to be shared and what needs to be allowed or denied from a reuse and redistribution standpoint.

Most of the hardware value provided by the Raspberry Pi is contained inside the Broadcom BCM2837 SoC (Raspberry Pi 3 and later, also used in some Raspberry Pi 2 revisions). This IC is not open sourced and for reasons that I am unfamiliar does not appear to have general market availability or documentation publicly available for it.

No major distributor lists this IC for sale, nor does Broadcom make the datasheet available for download on their website.

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