Re: [Qemu-devel] QEMU WIN32 Porting Installing W2K

[Karl Magdsick]

> > 3.    Is there a way to emulate an AS 400 System using
> > QEMU or other software?
> 
> what is AS 400?

AS/400 is an IBM operating system for mid-range servers that runs on
POWER chips.  As I remember, all processes run in a single address
space to eliminate TLB flushes in context switches, but page
permissions get changed by the kernel when switching between
processes.  I believe I was reading about the history of POWER/PPC and
learned that the POWER/PPC family encompases 3 overlapping instriction
sets, one of which is required for AS/400.

I believe the 604e and similar chips do not implement some of the
functions required for AS/400.  I'm not sure about G3s, but I doubt
it.  I believe QEMU emulates something G3-ish, so I don't think AS/400
will run on the QEMU-emulated PPC CPU.  However, I could very well be
wrong.

I just did a quick search, and didn't find anything useful about
AS/400.  IBM has something called OS/400 (now called i5/OS), but that
looks like something in the OS/370, OS/390 family.  I don't think
AS/400 is in the OS/370 family, but I could be wrong.  AS/400 may have
been phased out.

It would be really cool if eventually QEMU could emulate IBM POWER
based servers well enough to run IBM's hypervisor.  The hypervisor
virtualizes the hardware for the operating system(s) proper and
provides resource partitioning.  Imagine VMware slimmed down and
ported to run on the bare hardware so it doesn't need a host operating
system and you've got a hypervisor.  Generally, the hypervisor
logically partitions resources and runs a seperate operating system
inside each partition.  The Xen project is developing a hypervisor for
x86 hardware, but it requires minor patching of the guest kernels to
avoid certain instructions.  (VMware works very similarly to Xen, but
VMware scans and dynamically patches code at runtime.)  Anyway, being
able to play around with (emulated) high-end hardware that was
designed for hypervisors would be cool.


-Karl