[Cbe-oss-dev] Support for embedded SPU ELF in dynamic libs

[Ulrich Weigand]

Maynard,

> In one of the review comments to our OProfile-Cell SPU profiling patch
> (see below), you mentioned that we may have to handle "an embedded spu
> ELF file in a shared library object".  You state that our current
> OProfile implementation does not support such a model.  That's a true
> statement, since we were not aware of a requirement to support such a
> model.  I gave Brian Watt a call to ask what he knew about this, and
> he's not aware of anyone who's attempted to do this and wasn't sure if
> it's a supported model.  He suggested I ask Alan Modra, who I put on cc.

Embedding an SPU executable into a PPE shared library has always been
supported.  The result of ppu-embedspu is a PPE *object* file, which
can be freely linked into either executables or shared libraries.

There's a pretty natural use case why you want to have that option:
consider you want to implement a general-purpose (PPE) library that
uses SPE code for acceleration, for example an encryption library
that uses an SPE to perform the core algorithm.  The PPE library
should be able to transparently execute code on the SPE, and to
do so, it's natural to embed the SPE executable image into the
shared library itself.


Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

--
  Dr. Ulrich Weigand
  GNU compiler/toolchain for Linux on System z and Cell BE
  IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
  Phone: +49-7031/16-3727   ---   Email: Ulrich.Weigand at de.ibm.com