Re: A proposal - binary

From: Zachary Amsden
Date: Thu Aug 03 2006 - 14:45:04 EST


Antonio Vargas wrote:
I've been fishing in my mail archive and was unable to get any
discussion about abstract mmu... do you know where I can get more info
on that?

Here's one useful link:

http://lwn.net/Articles/124961/

- but there can be no progress until there is some kind of consensus on
what those are, and having an interface in the kernel is a requirement
for any deeper level of paravirtualization.

Zach

Here I'd like to say that I mentioned both mol and the sun T1 because
so far we haven't had any discussion on whether any of their
interfaces are worth copying for the x86 case. Also worth looking at
would be the work done by IBM for ppc64 and s390, especially the last
one is prone to be very optimised since their hypervisor work has been
proven to work for a very long time.

I sure don't mean to diss out both vmware and xen work on the field,
given the rocky nature of the x86 architecture, but maybe taking a
look at preexisting work can be a good idea if it hasn't been done
earlier

Almost nothing from any other architecture makes sense for x86. X86 is not a virtualizable architecture. It has both classical problems - sensitive instructions, and also non-reversible CPU state. Hardware virtualization is now making that easier, but simplifying the OS to avoid these problems is actually simpler and more efficient. PPC64 and S390 had the benefit of being designed with virtualization in mind, and they still have "paravirtualized" kernel architectures when you look at the lower layers.

Zach
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