4 Jan
2002
4 Jan
'02
4:40 p.m.
On Fri, 4 Jan 2002, Sean 'Captain Napalm'
Conner wrote:
I believe that in virtual-8086 mode, priveleged instructions (e.g. OUT)
cause a trap. The OS, having set up the appropriate trap gates, gets
control and decides what to do for these instructions.
There is a bit mask in the TSS (I think) that controls whether an I/O
will trap or be executed. Other privledged instructions will trap.
There is an
undocumented mode---real-32 bit (where the CPU is in
32-bit mode, but not running protected) but that's a hack and is
probably not recomended.
That's 'flat mode'.