[syslinux] Failed to allocate memory for kernel command line, bailing out

[syslinux at tsaunders.co.uk]

I am trying to add UEFI support to my existing PXE environment for 
kickstarting CentOS 7.0. With bios boot all is working well.

I have added syslinux.efi and ldlinux.e64 from syslinux 6.03 to my tftp 
server and altered my dhcp server to boot syslinux.efi. I get to my usual 
menu fine, the server downloads vmlinuz and initrd.img fine but then bails 
out with "Failed to allocate memory for kernel command line, bailing out".

I have tried simplifying my menu down to one option, removing all the 
options from my command line, tftp fetch of vmlinuz and initrd, http fetch 
of vmlinuz and initrd but nothing makes any difference. Does anyone have 
any idea what I can do to get to the bottom of this issue?

The server I am trying to kickstart is a Dell Poweredge r410 and it is 
booting from a Broadcom NetXtreme II Gigabit Ethernet (BCM5716C) if it 
makes any difference.

Tim