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Minimal Raspberry Pi VPU firmware

github.com

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Re: Minimal Raspberry Pi VPU firmware

#5

Post by revelation »

erikb wrote: post #2

What can one do with it? Is it like a bootloader? Sorry really not enough know-how.

It replaces the non-free binary blob on the Raspberry Pi that runs right after reset and initializes the processor. Modern complex processors require a specific and carefully orchestrated series of initialization steps to configure system clocks and ensure external RAM and other peripherals work correctly.

Of course no one in their right mind would use this reverse-engineered code here for any serious purpose. Instead, you dump the bastardized RPi platform (it's basically a video graphics card with an ARM bolted on) and use something actually free, like the BeagleBone.

Re: Minimal Raspberry Pi VPU firmware

#6

Post by david-given »

erikb wrote: post #2

What can one do with it? Is it like a bootloader? Sorry really not enough know-how.

The Raspberry Pi is really a VideoCore IV processor with an ARM bolted on the side. At power on, a boot ROM loads an embedded OS image into the VC4 processor. That then sets up the hardware, powers up the ARM, and loads the OS image into that. The VC4 then continues running in the background servicing RPCs from the ARM.

What this is is a replacement VC4 operating system image which just fires up the ARM with an embedded image, sets it running, and then halts (assuming I'm understanding the docs correctly); so it can't (yet) actually load an OS into the ARM from disk or respond to RPCs etc.

In practical terms, this is the biggest, most difficult step forward towards running an almost completely open system on the RPi. (It could also be used as the core of a proper operating system running on the VC4 itself, which could be rather interesting.)

Re: Minimal Raspberry Pi VPU firmware

#7

Post by rogual »

revelation wrote: post #5
erikb wrote: post #2

What can one do with it? Is it like a bootloader? Sorry really not enough know-how.

It replaces the non-free binary blob on the Raspberry Pi that runs right after reset and initializes the processor. Modern complex processors require a specific and carefully orchestrated series of initialization steps to configure system clocks and ensure external RAM and other peripherals work correctly. Of course no one in their right mind would use this reverse-engineered code here for any serious purpose. Instea…

Do you know if there's one of these boards on the market that has:

1. A GPU

2. No binary blobs, no reverse engineering?

Re: Minimal Raspberry Pi VPU firmware

#8

Post by wyldfire »

david-given wrote: post #6
erikb wrote: post #2

What can one do with it? Is it like a bootloader? Sorry really not enough know-how.

The Raspberry Pi is really a VideoCore IV processor with an ARM bolted on the side. At power on, a boot ROM loads an embedded OS image into the VC4 processor. That then sets up the hardware, powers up the ARM, and loads the OS image into that . The VC4 then continues running in the background servicing RPCs from the ARM. What this is is a replacement VC4 operating system image which just fires up the ARM with an embe…

> The Raspberry Pi is really a VideoCore IV processor with an ARM bolted on the side.

I knew that the bootloader worked that way but didn't think of it being that way until reading your comment. Interesting to think of the hierarchy that way.

Naively this makes me think that the ARM ISA could use something like UEFI (or BIOS) to unify the devices' bootstrapping logic around some common metaphor.

Re: Minimal Raspberry Pi VPU firmware

#9

Post by pingswept »

rogual wrote: post #7
revelation wrote: post #5

Earlier quoted context omitted.

It replaces the non-free binary blob on the Raspberry Pi that runs right after reset and initializes the processor. Modern complex processors require a specific and carefully orchestrated series of initialization steps to configure system clocks and ensure external RAM and other peripherals work correctly. Of course no one in their right mind would use this reverse-engineered code here for any serious purpose. Instea…

Do you know if there's one of these boards on the market that has: 1. A GPU 2. No binary blobs, no reverse engineering?

I believe the answer is no.

You might be interested in monitoring this list of what gets closest: https://www.fsf.org/resources/hw/single-board-computers

Also, the Novena mainboard has a chance of getting there, if you look at this page: https://www.kosagi.com/w/index.php?title=Novena_Main_Page and then note that the Vivante GPU is close to having free drivers: https://www.phoronix.com/scan.php?page=news_item&px=Etnaviv-...

Re: Minimal Raspberry Pi VPU firmware

#10

Post by abrodersen »

rogual wrote: post #7
revelation wrote: post #5

Earlier quoted context omitted.

It replaces the non-free binary blob on the Raspberry Pi that runs right after reset and initializes the processor. Modern complex processors require a specific and carefully orchestrated series of initialization steps to configure system clocks and ensure external RAM and other peripherals work correctly. Of course no one in their right mind would use this reverse-engineered code here for any serious purpose. Instea…

Do you know if there's one of these boards on the market that has: 1. A GPU 2. No binary blobs, no reverse engineering?

I think the Jetson TK1 from NVIDIA can run mainline Linux with most of the devices working.
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