Hello.
Quoted 2 lines · Paul Lyon
Did AMD just not include the microcode or
hardware support for shifting to virtual 8086 mode from 64 bit mode?
AMD answers your question here:
http://www.x86-64.org/lists/discuss/msg03333.html

Thanks for the reference. So the hardware is there, but apparently it is complicated enough, and slow enough, that the kernel coders decided not to bother with it. I wonder if the CPU designers could have made it simpler and faster if they had added some more transitors. Perhaps they decided that it wasn't worth the bother either.

Quoted 6 lines

Quoted 2 lines
If they don't manage to restore this feature, that may keep me from buying an Opteron motherboard for rather a while.
One can't always depend on the
legacy things. v86 can't live
forever.

Forever is a long time :-) For the present, there is rather a lot of DOS software outthere that is unlikely to be ported to, or adapted/upgraded to, more recent OS's, and if it is, it will be Win XP or some successor, not Linux. A lot of that is games, of course, but I would wager that most of the audience has some DOS games they would be reluctant to be unable to play anymore without booting back into plain old DOS. In my case, besides the games, there are two very useful programs, at least, that I use for writing and software development/documentation, at least one of which is still an unported dos program, and the other of which is, it seems, at present an unfinished Win32 port (no Linux users need apply :-( These are commercial packages from a small software house, but there is nothing comparable in the free software world.

Ciao,

Paul Lyon
http://www.la.utexas.edu/~plyon