iPXE iSCSI sanboot unreliable with 82573L at 1Gbit

[schubi]

Hello,

first of all, iPXE is a real, cool and fancy bootloader. Good work @ devel.

But, we got a big problem if we try to boot a Windows (7,8, 2008 (R2) or 2012 (R2)) on a mainboard equiped by an Intel 82573L NIC chipset.
Here are the symptoms.
We boot into an iSCSI target LUN , install Windows on it, everthing is fine. The installation succeeds. But then, some times, an iSCSI boot failed. The next iscsi boot works fine again, on the same machine, the same target, the same ipxe loader. It is impossible to say when will this boot succeeds of fails.

Deeper investigations showed that the problem only occurs if the link speed of the iscsi client interface is 1 Gbit/s. This problem only occurs on mainboards with the specified NIC 82573L, any other Intel NIC works without any problems. One workaround is to tear down the speed to 100 Mbit at boot time. Because as long as the speed is at 100 Mbit during the boot of Windows, it is safe to go up to 1Gbit while Windows is running.
Furthermore, we could see on tcp dumps that the iSCSI traffic suddenly stops without any idea why, when the boot failed. The iSCSI client stops to send iSCSI read requests.

So, as discussed in http://forum.ipxe.org/showthread.php?tid...ight=speed it would be a fix for us to set the link speed hard to 100 Mbit at iPXE boot time. Or, does anyone have any other idea to kill this bug or a better workaround? I hope it's obvious that changing the port speed at switch level everytime a boot occurs can't be a fix.
I'm looking forward to hearing of someone who wants to help me

If any further information is needed, I will provide them.