On Mon, 2011-07-18 at 10:47 -0500, Paul Gilmartin wrote:
> On Mon, 18 Jul 2011 10:34:52 -0500, John McKown wrote:
>
> >z/LINUX uses SVC to invoke the kernel.
> >
> >Which I find most interesting as it means that, theoretically, one could
> >write a z/LINUX ABI interface which uses Subsystem SVC screening to run
> >z/Linux applications on z/OS UNIX.
> >
> fork()? Pipes? Sockets? Environment variables? File access?
> EBCDIC<-->ASCII autoconversion? SYSCALLS back to Classic
> facilities and Classic Data Management?
Well the emulation should take care fork(), pipes, and sockets by doing
conversion from the Linux requirements to the z/OS requirements, then
invoking the z/OS equivalent (if any).
Classic facilities? Well, that's more difficult. Simplest would be to
declare the z/Linux to be a closed world with little or no interface to
classic stuff. Try to run a normal shell script and read a sequential
dataset.
Code translation is a PITA. Environment variables could be kept in
"native" code points for easy of use by Linux code. Create a new
facility in z/OS UNIX to access ASCII oriented environment variables.
Perhaps ${{varname}} instead of ${varname} which the z/OS UNIX shell
would recognize as "varname" needs to be translated to UTF-8 or Unicode
before doing a lookup in the environment table, then translate back to
the z/OS UNIX shell's code point for its value. As you say: "I hate
EBCDIC!"
>
> What are the advantages of PC over SVC? Why did Linux for z
> eschew PC and stay with SVC?
Don't know. Talk to IBM. Perhaps it was closest to what x86 uses, which
is the INT instruction (INTerrupt).
>
> -- gil
>
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--
John McKown
Maranatha! <><
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