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Re: Modified Linux 4.1.20 (mac+scsi) on Quadra 660av

On Wed, 3 Aug 2016, Mac User wrote:

> Would it make more sense to adapt the last working version of the ESP 
> SCSI code (apparently from kernel 2.6.30) or try to fix what is there 
> now (with the goal of having it work with Linux 4.x kernels)?

If you want other people to benefit from your work, and if you want to get 
the benefit of other people's work, then you'll want to collaborate with 
the upstream project.

That means working with kernel.org, and adhering to the development 
practices and standards required of contributions to that project.

> Is anyone working on this already?

Not AFAIK. The AV Quadras aren't very common, and this is likely to be a 
difficult bug to fix. If you don't already know your way around the kernel 
code base, the 53C96 (ESP236) hardware, and/or the SCSI standards, then 
the learning curve is probably not going to be rewarded.

> This also affects the Centris 650, perhaps all of the Quadra machines?

Did you test any of those machines? Last I heard, the mac_esp driver 
worked fine on non-AV Quadras.

> Is there a final Debian-approved version of a working ESP SCSI module 
> (from Linux 2.6.30 or later) that can be used as a starting point?

I'm not a Debian Developer, but the only "Debian-approved" code that I 
know of is the code that Debian ships. As a rule, Debian does not ship 
kernel patches that have not first been accepted by kernel.org. (This is 
just the nature of collaboration between open source developers, as 
opposed to "forking".)

> You said Apple didn't document their PSC chip very well; is there any 
> documentation at all that Debian can share?

The Peripheral System Controller (PSC) is a proprietary ASIC. It is surely 
well documented, but Apple does not share that kind of information with 
with customers, users or the open source community. (Aside: I'm guessing 
that this is also the reason why AOSP and cyanogenmod are not available 
for ipads and iphones.)


> thanks
> -Stan

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