Re: [9fans] Plan 9 on Blue Gene

["ron minnich" <rminnich@gmail.com>]

On Wed, Jul 30, 2008 at 8:25 AM,  <gdiaz@9grid.es> wrote:
> Hello,
>
> Just a dumb question, as i'm totally out of this business, it is easier to write an emulator than translate the applications to plan9 c ? (for example) or to write (or port) the C++ and Fortran compilers and related tools?

yes. I looked at the app mess for a while.

1. rewrite apps in plan 9 c. The Plan 9 C compiler is fine for what we
do on Plan 9. For scientific apps, it's not that great a compiler. The
IBM compilers know all the tricks. The effort to get Plan 9 C up to
the standards of XLC is mind-boggling. And XLF? We're not going to
write a Fortran compiler from scratch.
2. Port the compilers. Why, exactly? None of the users would be
willing to use a Plan 9 desktop.

>
> i'm asking from a technical point of view, i suppose dealing with the current users and customers is the real issue, right?

partly.

What we are really doing is using the Plan 9 os on blue gene as a
target from a cross-compiler, running on Linux. The tack I'm taking
(for now) is a system call compatibility interface in the kernel.
Recall how apps set themselves up to be debugged: write hang to ctl.
In this case, they write 'CNK' to ctl. After the exec, the system
calls are handled differently: have a Linux/gcc parameter interface,
and do different operations (some new), and will allow direct access
to the network interfaces.

We're helped by the fact that Compute Node Kernel (the lightweight
kernel for bluegene) doesn't support fork.

ron