kernel --timeout is not supported by ipxe-rom-qemu from RHEL7

[Gonéri Le Bouder]

A qemu node will fail to boot on RHEL7 is --timeout is in use:

ipxe-rom-qemu: 20130517-7.gitc4bce43.el7

=================
SeaBIOS (version seabios-1.7.5-11.el7)
Machine UUID e47e3482-9315-4c86-a512-224ba3610426

iPXE (http://ipxe.org) 00:03.0 C100 PCI2.10 PnP PMM+BFF97970+BFEF7970 C100

Booting from ROM...
iPXE (PCI 00:03.0) starting execution...ok
iPXE initialising devices...ok

iPXE 1.0.0+ (c4bce43) -- Open Source Network Boot Firmware -- http://ipxe.org
Features: iSCSI HTTP DNS TFTP AoE bzImage ELF MBOOT PXE Menu PXEXT

net0: 00:24:a1:f7:da:b6 using virtio-net on PCI00:03.0 (open)
  [Link:up, TX:0 TXE:0 RX:0 RXE:0]
DHCP (net0 00:24:a1:f7:da:b6)............... ok
net0: 192.0.2.29/255.255.255.0 gw 192.0.2.1
Next server: 192.0.2.1
Filename: http://192.0.2.1:8088/boot.ipxe
http://192.0.2.1:8088/boot.ipxe... ok
inc: command not found
pxelinux.cfg/00-24-a1-f7-da-b6... ok
DHCP (net0 00:24:a1:f7:da:b6)............... ok
Unrecognised option "--timeout"
Usage:

  kernel [--name <name>] [--autofree] <uri|image> [<arguments>...]

See http://ipxe.org/cmd/kernel for further information
Could not boot: Invalid argument (http://ipxe.org/1c162202)
PXE boot failed! No configuration found for NIC 00-24-a1-f7-da-b6.
Please update your iPXE ROM and retry.
Press any key to reboot...
Could not boot image: Connection timed out (http://ipxe.org/4c22e035)
No more network devices
=================

This makes the use of the ipxe_timeout parameter complicated. We should be able to chainload to a up to date IPXE undionly.kpxe to avoid this situation.

[Dmitry Tantsur (divius)]

I don't think we can do anything, except for documenting that ipxe_timeout requries a new ROM. We already have a couple of work arounds in place for the CentOS/RHEL.

[Gonéri Le Bouder (goneri)]

This issue impacts TripleO, not Ironic, because it prevents us from adjusting the ipxe_timeout value.
https://review.openstack.org/#/c/294787/