Messages in this thread |  | | From | (John G. Alvord) | Subject | Re: Linux for JavaVM | Date | Wed, 08 Jan 1997 04:41:51 GMT |
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On Tue, 07 Jan 97 22:00:17 +1000, bofh@snoopy.virtual.net.au wrote:
> Running Linux in Linux in Linux would be a great thing! I've been reading >reports about how IBM's older mainframes worked and specifically about the >architecture of VM/DOS. Apparently they had a virtual machine which the OS ran >in, the VM provided file access and linear memory to the OS. I did a lot of work on that system, called VM. There was a control program (CP) which ran virtual machines. It was all written in S/370 assembler and was about 300K lines of code (VM and the user interface called CMS which had a file system, an exec language, and little else). Of course that excludes compilers, etc.
Most of the work was a detailed simulation of memory and I/O. S/370 I/O is complex, involving channel programs (you don't want to know). It also simulated privileged instructions. The result was sufficient to run VM under VM, which was a marvelous development environment. Imagine single stepping, breakpointing, etc at the kernel level.
A big project to duplicate. Incidently, VM still exists and is being enhanced even today.
john alvord
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