Intel D2500CC motherboard and strange RS232/UART behavior

Weiß, Jürgen weiss at uni-mainz.de
Fri May 24 19:15:21 UTC 2013


According to the ACPI of the board, uart0 and uart 2
use IRQ 3 and
     IRQ (Edge, ActiveLow, Shared, )
       {3}
uart1 and uart3 use IRQ 4
     IRQ (Edge, ActiveLow, Shared, )
       {4}

ioapic_config_intr is called with trig == INTR_TRIGGER_EDGE and
 pol == INTR_POLARITY_LOW.

The combinatation of Edge and ActiveLow seems kind of broken.

Forcing the polarity in ioapic_config_intr to INTR_POLARITY_HIGH
and disabling uart 2 and uart 3 results in two working serial
interfaces.

So what is the correct fix to this?

Regards 

Juergen Weiss

Juergen Weiss      |Universitaet Mainz, Zentrum fuer Datenverarbeitung,
weiss at uni-mainz.de |55099 Mainz, Tel: +49(6131)39-26361, FAX: +49(6131)39-26407




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