Unusual fxp behaviour with link0 flag

I just noticed some unusual behaviour when running an fxp with the link0
flag set (interrupt coalescing microcode enable).

fxp0: <Intel 82550 Pro/100 Ethernet> port 0xd000-0xd03f mem 0xe3000000-0xe301ffff,0xe3020000-0xe3020fff irq 10 at device 10.0 on pci0

fxp0_at_pci0:10:0: class=0x020000 card=0x00508086 chip=0x12298086 rev=0x0d hdr=0x00

That's the specific revision in question, it's an 82550GY if memory serves
correctly.

Ah well. If only someone would offer me a truckload of em(4)'s (fell off
the back of a lorry, guv'nor).

BMS