Messages in this thread | | | Date | Thu, 17 Jan 2008 00:34:05 +0100 | From | Rene Herman <> | Subject | Re: [patch 2/2] 8250_pnp: register x86 COM ports at the conventional ttyS names |
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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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