8139c+ mii bug?

[Paul <mirnshi@xxxxxxx>]

Today I test the DragonFly on a box, the nic is 8139c+.
But the driver of 8139c+ can not detect the status of link.
FreeBSD 4.11 is same.

If I commented the next lines, FreeBSD 4.11 and DragonFly fit 8139C/D/C++ 
nicely.

/sys/dev/mii/rlphy.c in FreeBSD, /sys/dev/netif/mii_layer/rlphy.c in 
DragonFly, function void rlphy_status(phy):
. .....
if (bmcr & BMCR_ISO) {
	mii->mii_media_active |= IFM_NONE;
	mii->mii_media_status = 0;
	return;
}
. .....

I checked the driver in linux, it does not check BMCR_ISO. BTW, a guy had a 
bug report of FreeBSD: kern/76710.

So why BSDs check this?