Intel PCI-X, Intel Gigabit Ethernet Controllers manual IMC Register Bit Description

Register Descriptions

Software should write a 1b to the reserved bits to ensure future compatibility. Since this register masks interrupts when 1b is written to the corresponding (defined) bits, then writing 1b to the reserved bits ensures that the software is never called to handle an interrupt that the software is not aware exists.

Note: For the 82547GI/EI, programmers need to first write (clear) the IMS and IMC registers due to a Hub Link bus being occupied. This results in an interrupt de-assertion message that can’t to be sent out. When a future interrupt assertion message is generated, two messages are re-ordered and sent out. This signals APIC that the 82547GI/EI is in a de-asserted state when it is actually in an asserted state, which causes a system dead lock. To avoid a system dead lock, first clear the IMS and IMC registers by writing FFFFh and then re-assert IRQ enable.

Table 13-66. IMC Register Bit Description

31 17 16 0

Reserved

IMC Bits

Field	Bit(s)		Initial	Description
			Value
TXDW	0	X		Clears mask for Transmit Descriptor Written Back.
TXQE	1	X		Clears mask for Transmit Queue Empty.
LSC	2	X		Clears mask for Link Status Change.
RXSEQ	3	X		Clears mask for Receive Sequence Error.
				This is a reserved bit for the 82541xx and 82547GI/EI. Set to 0b.
RXDMT0	4	X		Sets mask for Receive Descriptor Minimum Threshold hit.
Reserved	5	X		Reserved: Should be written with 1b to ensure future
				compatibility.
RXO	6	X		Clears mask for on Receiver FIFO Overrun.
RXT0	7	X		Clears mask for Receiver Timer Interrupt.
Reserved	8	X		Reserved: Should be written with 1b to ensure future
				compatibility.
MDAC	9	X		Clears mask for MDI/O Access Complete Interrupt.
RXCFG	10	X		Clears mask for Receiving /C/ ordered sets.
				This is a reserved bit for the 82541xx and 82547GI/EI. Set to 0b.
Reserved	11	X		Reserved: Should be written with 1b to ensure future
				compatibility (not applicable to the 82544GC/EI).
PHYINT	12	X		Clears PHY Interrupts (not applicable to the 82544GC/EI).
				This is a reserved bit for the 82541xx and 82547GI/EI. Set to 0b.
GPI	14:11	X		Clears General Purpose Interrupts (82544GC/EI only).
GPI	14:13	X		Clears General Purpose Interrupts.

Software Developer’s Manual 295