iSCSI disconnect problem with ipxe but not with gpxe

[mammerlaan]

I've been trying to install Windows using pxe chainloading (undionly.kpxe) with an embedded script to sanboot with a fallback to a local cdrom drive.

ipxe from master (dated 20160616) can connect to the iscsi target and falls back to cdrom (as the image is empty). Trying to use the iscsi target from the installer is excruciatingly slow. Looking in the logs for the target (a synology/Linux/LIO scsi target) I see many login/closes happening. After a few hours the partitions have been set up. After that I aborted it. Another iSCSI target (istgt from nas4free) shows the same problem. The interval between login/close is 20 secs. which matches the NOPIN interval.

When I use the ancient gPXE in the same way it does not show this behaviour. Seems like a regression happened somewhere the last 5 years.... Does anybody have an idea what could have caused the regression? I can retest easily enough, but going through 5 years of commits seems like a lot of work.