On 16-01-08 21:42, H. Peter Anvin wrote:
Bodo Eggert wrote:
BTW1: These addresses may be used to detect ports on non-standard
addresses, but unfortunately they don't tell the IRQ.
BTW2: When I submitted a patch using the BIOS data area, I was told
that it might not exist on systems booting from non-PC firmware. This
claim was not yet backed with any knowledge, nor did anybody suggest a
way to detect this situation.
This is, of course, true. It doesn't exactly help that some (most?)
non-PC firmware at least mimic the BIOS data area.
In this particular case, there is some minor sanity-checking that can be
done: the values should be nonzero and aligned 8.
The number of places expected to contain something sensible should I believe
first be verified at 0x410 -- the equipment word. Bits 11-9 (0x0e00) should
be the number of serial ports, 0 to 4 (so 5-7 is also a sanity check) and if
BIOSes can be expected to zero out the non-used base-addresses (at 0x400,
0x402, 0x404, 0x406) that's another sanity check. Don't know if they can
though...
Rene.
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