Unable to use pxelinux's sanboot.c32 or gpxecmd.c32 to boot iscsi target with chap

[ccy]

I compile latest undionly.kpxe from latest ipxe source. I attempt to boot a iscsi target with chap secret using:

iPXE> dhcp net0
iPXE> set username = user1
iPXE> set password = password
iPXE> sanboot iscsi:192.168.0.1::::iqn.example.com:win7

The machine boot properly from iscsi target.

Next, I try to chain load the ipxe from pxelinux:

LABEL ipxe
kernel undionly.0

and boot the following script via dhcp (using the infinite loop prevention method):

#!ipxe
dhcp net0
set 190:string user1
set 191:string password
set 209:string menu.cfg
chain pxelinux.0

And the following menu.cfg is loaded:

UI menu.c32

LABEL Windows_1
com32 gpxecmd.c32
append sanboot iscsi:192.168.0.1::::iqn.example.com:win7

LABEL Windows_2
com32 sanboot.c32
append iscsi:192.168.0.1::::iqn.example.com:win7

Executing both Windows_1 or Windows_2 doesn't boot the iscsi target and no message was prompt.

Any ideas what could be go wrong?

If I remove the chap secret from iscsi target, the iscsi target works fine both ipxe direct boot or chain load.

My PXELinux is version 4.04.