+++ /dev/null
-.TH realemu 8
-.SH NAME
-realemu \- software emulation of /dev/realmode
-.SH SYNOPSIS
-.B aux/realemu
-[
-.B -Dpt
-] [
-.B -s
-.I srvname
-] [
-.B -m
-.I mountpoint
-]
-.SH DESCRIPTION
-.PP
-Originally, kernel provided
-.B /dev/realmode
-files with the
-.IR arch (3)
-device to access and call the
-.SM BIOS.
-.PP
-Interrupts had to be disabled and the processor was switched in the
-legacy 16-bit
-.SM realmode
-with memory protection disabled to execute
-.SM BIOS
-code.
-.PP
-This is problematic in case the
-.SM BIOS
-reprograms hardware currently
-used by the operating system or when it reenables interrupts or just
-crashes. This will freeze or reboot the machine with no way to
-recover or diagnose the problem.
-.PP
-To avoid this,
-.I realemu
-is used to emulate the execution of the
-.SM BIOS
-routines by interpreting the machine instructions and intercepting
-dangerous actions that would compromise the systems stability.
-.PP
-Running
-.I realemu
-with no arguments, it mounts itself before
-.B /dev
-and
-replaces the original
-.B /dev/realmode
-file in the current namespace.
-.PP
-Then programs like
-.IR vga (8)
-can use it to make ther
-.SM BIOS
-calls.
-.PP
-The
-.B D
-flag will enable debug messages for 9P. The
-.B p
-and
-.B t
-flags
-control tracing of i/o port access and cpu instructions to
-stderr (fd 2).
-.PP
-When a
-.I srvname
-is given with the
-.B s
-argument, the default
-.I mountpoint
-is ignored and a
-.SM 9P
-channel is created in
-.B /srv
-that can be used to mount
-the filesystem from another namespace. If a
-.I mountpoint
-is given before
-the
-.I srvname
-argument then it is ignored, otherwise it will be used.
-.SH EXAMPLES
-The
-.I realemu
-process is only needed when accessing
-.B /dev/realmode.
-To invoke a subshell so that
-.I realemu
-exits normally after
-.B aux/vga
-completes:
-.IP
-.EX
-% @{rfork n; aux/realemu; aux/vga -m vesa -l $vgasize}
-.SH SOURCE
-.B /sys/src/cmd/aux/realemu
-.SH "SEE ALSO"
-.IR vga (8),
-.IR arch (3)