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Re: [Xen-devel] What is machine address?

How does Plan 9 efficiently handle a large number fragmented memory
ranges? FreeBSD can do it, but not well enough to eliminate the PA/MA


On Thu, 16 Sep 2004, Ronald G. Minnich wrote:

> MA = machine address
> PA = physical address
> VA = virtual
> On Thu, 16 Sep 2004, Steven Hand wrote:
> > Physical address = address of a piece of memory used by a guest operating
> > system (starting at 0 and going up to the amount of memory you have in
> > that particular virtual machine).
> On real machines, PAs == the real hardware.
> On Xen domains, PAs == not real hardware.
> Xen actually virtualize physical addresses, so although the PA range in an
> OS may be linear and contiguous, the underlying MAs are not.
> At some point I want to fix up Plan 9 to ignore PAs entirely and just VA
> and MA, but that's for later. The concept of a PA has no real meaning
> anyway at this point, so I see no reason to deal with it.
> ron
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