> > CLI/STI and stuff. IOPL < CPL means that the I/O permission bitmap is
> > consulted, and CLI/STI trap.
> And that's the sane situation - as long the bitmap is used, the kernel is
> safe.
but you'd need a huge bitmap for 64k ports for many (not too recent) cards
because of the great sparse IBM 8514A register layout:(
and in/out instructions take quite a few more cycles for every bitmap access.
and this all won't protect your system from graphics chips going cracy and
locking up e.g. the PCI bus due to bad values in correct registers
(not an uncommon problem at least for S3 chip;)
Harald
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