[Ardour-Users] Can anyone help with a Linux problem ?

Mark Greenwood fatgerman at ntlworld.com
Sat May 30 02:32:30 PDT 2009


On Friday 29 May 2009 21:43:29 Mark Knecht wrote:
> On Fri, May 29, 2009 at 1:31 PM, Rob Quin <robquin at uklinux.net> wrote:
> > On Thursday 28 May 2009 18:36, Mark Knecht wrote:
> >> >> I'm sure you probably know this but the closed-source driver cannot be
> >> >> shown to be rt-kernel safe
> >> >
> >> > Some people reported that and others reported it's fine.
> >>
> >> How does anyone other than NVidia be able to report it's rt-safe? Only
> >> NVidia can see the code.
> >
> >
> >
> > I don't have any useful suggestions on the topic of this thread but I would
> > like to try and prevent this missinformation from spreading. This is the real
> > situation.
> >
> > The Nvidia code is copyrighted to Nvidia and not open source.
> > However the source is published by Nvidia and widely available so anyone can
> > inspect it,
> 
> Interesting, and if true then that's great.
> 
> My understanding is a bit different, but I'm open to be educated.
> 
> First, there are two portions to the nvidia driver:
> 
> a) A portion distributed as source. This portion is certainly human
> readable and it's function is to interface a lower level portion with
> your kernel. This portion can be inspected for rt safeness.
> 
> b) A second portion that is distributed in binary. This portion does
> all the low-level, CPU/GPU intensive work. My understanding is that
> this is where the nvidia intellectual property is and they keep that
> private and, TTBOMK, cannot be inspected.

Mark's correct. The NVIDIA driver is often known as the 'blob' driver for that reason. The kernel interface parts are distributed as source so they can be compiled against your kernel (eg by dkms). The low level hardware driver is a big lump of binary. If you go over to kernel.org they won't listen to bug reports raised if you are using the nvidia driver because they have no way of knowing what it's doing.

All that said, I've been using it on my audio setup for a couple of years. Jack reports my latency as 0.8ms and I don't have any trouble. 

Mark

> 
> To the best of my knowledge the second portion hasn't ever been
> distributed in source. It's presumably not even completely C code.
> 
> But again, if I'm wrong about that then I'd be very interested in
> getting the story right. I'm not a coder and wouldn't have had any
> reason to go any further, but that's the story I've been told over the
> years.
> 
> Cheers,
> Mark
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