> Yes - it is a work around for broken/incomplete emulation or incorrect > interrupt routing. Always doing this would result in a performance hit on all > systems. As shown in your dmesg, both em(4) devices are using the same IRQ:
Long time ago I tried five Intel network cards in the same computer, i386. I never succeded to have more than two together. It was always about IRQ problems, reported by BIOS. I tried even a firmware update for the cards, but no luck. No luck in configuring BIOS, too. Then I discarded them and replaced all with five 3Com. They worked from the first start without a problem, for years. I heard Intel cards are the best in high packet pushing, but no use if they are not able to work together.
