Network iPXE Intel 82579LM HP IRQ Polling mode fix


 * Note a somewhat more professional fix is now committed in the iPXE tree

This is a patch I made to allow iPXE booting of certain Intel 82579LM NIC based HP laptops (6570b, 2170b, xx70x et al.) that have firmwares that tell fibs. (In a nutshell - They claim that IRQs are supported, but then never generate interrupts.)

Some examples (afraid my notes were rather poor here as I write it up, I didn't denote which code was which laptop)

(Windows) VEN_8086&DEV_1502 VEN_8086&DEV_1503

(Linux) 8086:1502 103c:1618 8086:1502 103c:17a7 8086:1502 103c:1815 8086:1503 ???

I think it has been a problem for quite a while (and with other cards) that previously had no fix. I hope this may help people who come across the problem be able to see how it manifests itself.

You will get the message up like this with a load of dots until it just stops. Simplistically - its working initially from a PXE F12 style boot, gets a DHCP response, boots iPXE, but then iPXE is waiting for an interrupt that never comes so cant contact the DHCP server again and times out.

DHCP (net0 10:60:4b:48:7c:08)..........

This is the patch that just does the overriding based on the vendor and device PCID codes matching