[raspi-internals] Re: Hey, look, QPU docs

  • From: David Given <dg@xxxxxxxxxxx>
  • To: raspi-internals@xxxxxxxxxxxxx
  • Date: Fri, 28 Feb 2014 23:30:27 +0000

On 28/02/14 22:44, David Given wrote:
> However they've also released a big chunk of source code which seems to
> include VC4 assembly:
> http://www.broadcom.com/docs/support/videocore/Brcm_Android_ICS_Graphics_Stack.tar.gz

This *does* contain headers for all the weird registers. I now know what
the mysterious hardware module at 0x7ee06000 is called, for example.
Unfortunately while it names the registers it doesn't seem to go into
any bit-level detail --- although *other* modules do.

There's a README that says that all the headers are autogenerated from
<location>. <location> is not in the source release. The source is a bit
of a mess --- I've found the same register documented in three different
headers, for example. I think it's been fairly hurriedly constructed out
of an Android source tree.

The good stuff seems to be in bcrm_usrlib/dag/vmcsx/vcinclude.

The bad news is that there's no well-documented license anywhere, which
is why this message is rather skimpy on technical details. Some files
have a boilerplate 'Copyright Broadcom All Rights Reserved' header at
the top. There's a tonne of open source stuff, mostly 3-clause BSD (also
copyright Broadcom). Some say they're confidential. Some files have
nothing at all. All I can say here is... *shrug*

Oh, yeah, and I recognise the RTOS.

And it also looks like while the source to the RTOS is there, it's
missing the critical startup code which initialises the RAM. [sad face]

Now I need to go to bed. I keep finding fascinating stuff in here.

┌─── dg@cowlark.com ───── http://www.cowlark.com ─────
│ "There does not now, nor will there ever, exist a programming
│ language in which it is the least bit hard to write bad programs." ---
│ Flon's Axiom

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