[Discuss] VMWare Player question

[gaf at blu.org (Jerry Feldman)]

On 10/19/2011 08:20 PM, Richard Pieri wrote:
> On Oct 18, 2011, at 8:56 PM, Edward Ned Harvey wrote:
>> Nothing will support a 64bit guest on a 32bit host.
> I digress here, because this is not strictly true.  IBM devised a method for running some 64-bit applications on 32-bit AIX servers.  I digress because this was not virtualization.  It was a clever use of a wrapper that mapped 64-bit functions to their 32-bit counterparts and then mapped the returns back as 64-bit data.  It was terribly slow, totally unsuited for production use.  IBM did it for developers to test their code given older hardware.
>
> VMware could have made it happen.  Back before VT-x and AMD-V, VMware didn't really virtualize the x86.  VMware *emulated* the x86.  Ask Google about trap-and-emulate and why it doesn't work on the Intel architecture.  That's why-for the roughly 50% performance hit compared to what we have today with VT-x/AMD-V.  VMware could have incorporated AMD64 in their x86 emulator.  It would have been abominably slow, much like IBM's 64-bit to 32-bit mapping trick.  VT-x and AMD-V made this a non-issue.
There are 2 BIOS flags in the Thinkpad, VT-d and Virtualization. Both
have to be set for Pl;ayer to host 64-bit guests.


-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
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