Messages in this thread |  | | Subject | Re: Simple patches for Linux as a guest OS in a plex86 VM (please consider) | From | Valdis.Kletnieks@vt ... | Date | Fri, 24 Jan 2003 14:01:44 -0500 |
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On Fri, 24 Jan 2003 08:52:46 PST, Kevin Lawton said:
> About 99% of the work of a full x86 VM is on handling less > than 1% of the cases. So the new plex86 angle is, forget doing > all the fancy work for 1%. If you're running a VM friendly OS > (like Linux with my small patches), you end up with a potentially high > performance and Open Source VM, with very little work.
One of the first implementations of VM was by IBM, called CP/67. It eventually evolved into VM/370 and its follow-ons.
The initial design reason for CP/67 was to allow 2 or more MVS development teams to share a system for testing, so the other team could keep working while the first team debugged a system crash with tools better than the lights-n-switches at the console.
It turns out that the 99% of the work to cover the 1% of the cases is really important. The usual reason for doing VM is to isolate images from each other - and if you don't cover that last 1%, a programming error in one of the images can nuke your supervisor code into oblivion. It may be a "VM friendly OS like Linux", but it can still oops in strange ways. For starters, what happens if you run a Linux *without* your patches under plex86? ;)
Now if you think about it, and not covering the 1% case is deemed acceptable, that's OK too. But it's something that needs to be considered. -- Valdis Kletnieks Computer Systems Senior Engineer Virginia Tech
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