Re: [9front] termrc and aux/realemu

[cinap_lenrek@felloff.net]

every video mode is special. aux/vga does special stuff for
every one of them like mapping mmio registers from named
hardware segments or reading/writing special control files
of the kernel half driver. vesa works with doing vesa bios
calls. /dev/realmode was initially provided by the kernel,
by doing a mode switch to realmode and executing the code.

with realemu /dev/realmode is provided by userspace fileserver
which binds over /dev and hides the kernel mode /dev/realmode
files.

these days, 9front has no kernel mode /dev/realmode anymore
as realemu works good enougth and realmode isnt even available
in 64 bit kernel. the modularity remains. this is good for
debugging, as you can run realemu with tracing modes
that let you see what io ports are read and written by
the video bios code. also, mounting and unmounting lets
us make snapshots of the bios memory areas to rerun tests
from a defined state the video bios memory. (theres the
vbt program and scripts to try to bruteforce hidden video
modes that uses this).

conflating aux/vga with realemu isnt right in my opinion.
realemu can be used in many different ways and is not limited
to running vesa bios code (see comload) and aux/vga has no
need to depend on it directly.

--
cinap