RE: [RFC 0/8] Introducing a generic AMP/IPC framework

[Grosen, Mark]

> From: Ohad Ben-Cohen
> Sent: Saturday, June 25, 2011 6:12 PM
> 
> Hi Stephen,
> 
> On Fri, Jun 24, 2011 at 11:16 PM, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote:
> > Instead of devising a new firmware format, we decided
> > to just stick with elf and parse the headers in the kernel because we
> > needed them for authentication anyway. Is this reason enough to move to
> > an ELF format instead?
> 
> I think that consolidation of code is enough reason to make an effort.
> I know that our firmware format was chosen for simplicity, but I'm not
> sure if we have the tools yet to build standard ELF files for the
> remote processors (IIRC it's in the works though). I'll let Mark
> comment this one.

Yes, we are converting from "standard" ELF to the simple format. I've used the
GNU binutils to work with our ELF files. There were a few motivations:

1. Concern about complexity of parsing ELF files in kernel; however, the PIL
implementation looks pretty clean to me.

2. We added a special section (resource table) that is interpreted as part
of the loading process. The tool that generates our simple format just
recognizes a named section (".resource_table"), so perhaps that could be
done with the PIL ELF loader.

3. Smaller firmware file sizes. Our ELF files are large relative to the
payload, but this might be addressed by a better ELF "strip" utility.

> > Another difference is inter-processor dependencies. For example, on
> > msm8660 the modem can't boot until the dsp has been booted. I suppose we
> > could hide this detail in the platform specific get() implementation by
> > calling rproc_get() on the dependent processor (hopefully no locking
> > issues arise). I'd rather have it built into the core though as it isn't
> > really specific to the hardware.
> 
> No problems, I'm sure we can solve this one easily.
> 
> > If we can resolve these differences I think we can easily support remote
> > processor boot on MSM via remoteproc.
> 
> That'd be very cool, I sure do hope we can work together.

Yes, I hope we can merge our efforts on PIL and remoteproc since they seem
quite close in function and design.

Mark
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