Quote from KanjiMonster on August 30, 2011, 15:48
Quote from jamesh on August 26, 2011, 13:15
Quote from KanjiMonster on August 25, 2011, 12:14
Quote from jamesh on August 16, 2011, 22:39
It doesn't really matter what those guys do to be honest. On this device, there will be FOSS drivers that talk VCHIQ message passing to the GPU, on which will run a binary blob. It just so happens that in the architecture of the Videocore, it uses a set of hardware blocks and multiple processing units that accelerate various features, these are all coordinated by code running on the GPU processors itself, not the driver. This stuff is set off by the VCHI messages from the host (the Arm).
So if I understand you right, the proprietary blob is only running on the GPU/Videocore (basically a "firmware" for it), and everything on the host/arm side (kernel + user space) is actually open source?
That is my understanding.
This sounds to me like you are only guessing from what others said and don't know it for yourself.
Could perhaps a developer with first-hand experience confirm or deny this?
It would require some people very acquainted with the VideoCore and its various cores (it's a multiple custom core device in itself) and HW blocks, and the only people like that work for Broadcom! Also, to work on it you require a custom compiler, assembler, debugger, and expensive JTAG's etc.
These people do not only work for Broadcom; there are many with the appropriate skills working on and around the Linux kernel. If there's proper documentation (source code optional
) they will come.
There is a lot of very clever and proprietary stuff in there (HW and SW) which could be copied by competitors if it was out in the open, which is why it remains a binary blob. And why the Videocore remains top of class in what it does.
That's still protected by patents even when opened, so competitors still couldn't just copy it (at least not without potential legal consequences).
Not opening it also doesn't really put a stop on competitors finding out how it works; there are services that will analyse chips for you.
Hello, one of the developers here....well, sort of....
re: the team working on the chip. I'm sure there are a few smart people out there, who, after a couple of years training would be able to work on some of the more complex parts of the Videocore. I've worked in various areas in it for three years, and most of it is still a mystery to me. There are a lot of custom HW blocks which are not found in any other chip - and in order to use them you need to know about them. The codecs are a case in point, and some of the HW accelerated parts of OpenGL etc. The team here in Cambridge is about 100 people, covering hardware and software design, so there is a lot of experience here. There are a few ex-Videocore engineers out there, but not many.
Patents are a good protection, but you cannot patent everything (whatever Apple would have you believe) - it's not cost effective. It's cheaper to maintain secrecy over the HW and SW design than to fight patent wars. Put it like this, if another company copied part of the GPU, then stayed closed source, Broadcom might never know they had ripped off their code/HW design, so you wouldn't be able to fight a patent action anyway.
And good luck to a chip analysis firm who can figure out how a Videocore works by staring at it, in a sensible timescale (i.e. years).
I think that the FOSS or not status of the Linux side libraries is still being discussed, so I may have been premature in saying they would be FOSS (hence my statement 'That is my understanding'), but I think the explanation above should be enough for most people to persuade them that it is not actually necessary for them to be FOSS for the majority, if not all, the users, since there is very little they could do to them to make any difference anyway. If it works, and works as fast as it can, you really don't need access to the source, since the only reasons for access would be for making improvements or fixing bugs. And since Broadcom are fixing bugs and improving it all the time anyway.....
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed. Here's an example...
“I own the world’s worst thesaurus. Not only is it awful, it’s awful."