Linux starts UP then and uses 8259A interrupt controllers which have to work due to the DOS compatibility.
DAMNIT! I wish I could go back in time to 1978 and show microsoft how to write a good unified driver and GFX library architecture so that all programs would be written to use a single portable interface so we could have 32 peer interrupt channels (no cascading) and a full 16 DMAs. =((((((((((((((
Just for fun: rewrite your autoexec.bat to read:
" Mem /c > prn "
turn your printer on, yank out your video card and then boot... You get like 900k of somewhat usable DOS memory! =) I have proof that this works, it is hanging on my wall! =)