Originally, the kernel provided /dev/realmode and /dev/realmodemem
files via arch(3). These devices provided access to real mode
memory and BIOS calls.
Interrupts were disabled and the processor switched to 16–bit "real
mode" to fit the BIOS api. If BIOS reprograms hardware in use or
reenables interrupts or crashes, the system may freeze or reboot
with little ability for diagnosis or recovery. To avoid this,
realemu emulates BIOS by interpreting the code intercepting
dangerous actions that could compromise the system.
With no arguments, realemu mounts itself before /dev and serves
/dev/realmode. Flag D will enable 9P debugging; flag p traces
i/o port access; t traces instructions. The –s flag causes realemu
to post its channel on /srv/mntpt and the default mntpt is ignored.
If mntpt is given before srvname argument
then it is ignored, otherwise it will be used.|