Re: How to compile amd64 package from i386 source
On Fri, Mar 30, 2007 at 08:15:18AM +0000, A J Stiles wrote:
> I always thought that once the AMD64 processor was operating in 64-bit mode,
> certain 32-bit instructions were no longer available -- and the transition
> was an irreversible one.
No, not quite. You loose VM86 I believe, so no 16bit code support at
all.
It is also recomended that 64bit code doesn't use x87 instructions (and
both Windows and Linux make that recommendation mandetory by not saving
x87 registers on context switches of 64bit code). Of course x87
registers disappearing means MMX is gone too (not that it will be missed
by anyone).
So 32bit code should run just fine, with the kernel able to handle
context switches as needed for both 32 and 64bit applications.
--
Len Sorensen
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