must have limit 0xffff and attribute G = 0 (byte granularity) as well
as other properties that they already had (see e.g., the Intel i486
manual section 22.5). Not restoring them broke Ctrl-Alt-Del in the
bootstrap for my ASUS P55TP4XE system, probably because the Award BIOS
does anti-tracing stuff involving inaccessible %esp's.
asm.S:
Don't use lret in prot_to_real(). This reduces the risk of using an
incompletely intialized stack segment and saves space.
Submitted by: "K.Higashino" <a00303@cc.hc.keio.ac.jp> (on 13 Jan 1995!)
reworked by me
c50f3ecf5a