Friday, December 02, 2011

iPXE: Boot iPXE Linux kernel via PXELinux

iPXE Linux kernel (ipxe.lkrn) may chain loaded by PXELinux:

default boot

label boot
        kernel ipxe.lkrn

Both iPXE firmware (undionly.kpxe) or iPXE kernel image (ipxe.lkrn) has same functions. All usage of iPXE commands / scripts remain the same for both firmware and kernel.

Problem with Dell Vostro notebook

All the time I use PC with iPXE firmware (undionly.kpxe) with WinPE and SanBoot without problem. If I boot Dell Vostro notebook with the same booting steps as PC, the WinPE or SanBoot doesn’t work at all. The reason remain unknown. Here are my booting steps:

Scenario A

Switch on machine
DHCP –> undionly.kpxe (undionly.0)
Chain to load WinPE image
Show blank screen after WinPE image

Scenario B

Switch on machine
DHCP –> undionly.kpxe (undionly.0)
sanboot iSCSI target
Machine hang while booting

Both scenario A and B works fine on PC but doesn’t work on Dell Vostro notebook.

I suspect the problem is related to:

iPXE firmware
Notebook network card’s firmware doesn’t work well with iPXE firmware.

Dell Vostro notebook work with iPXE kernel

While trying to find solution solving the mystery problem with Dell Vostro notebook, I found that iPXE kernel works. I may load WinPE image or SanBoot a Windows ISCSI target with iPXE kernel chain loaded by PXELinux.

Prepare ipxe.lkrn

-bash-4.1$ git clone git://git.ipxe.org/ipxe.git
-bash-4.1$ cd ipxe
-bash-4.1$ make src/bin/ipxe.lkrn

Copy src/bin/ipxe.lkrn to TFTP boot directory.
```
# cp src/bin/ipxe.lkrn /var/lib/tftpboot
```

Update dhcp configuration file: /etc/dhcp/dhcpd.conf to prevent infinite iPXE boot when ipxe.lkrn boot:

        if exists user-class and option user-class = "iPXE" {
                filename "http://<ip-address>/boot.ipxe";
        } else {
                filename "pxelinux.0";
        }

Load ipxe.lkrn after PXELinux boot:

# cat pxelinux.cfg/default
default boot

label boot
        kernel ipxe.lkrn

iPXE kernel will query DHCP server again, DHCP will send boot.ipxe script file via HTTP to the machine:

#!ipxe
set 209:string pxelinux.cfg/boot
set 210:string http://<ip-address>/
chain ${210:string}pxelinux.0

boot.ipxe will chain load pxelinux.0 with new configuration file: pxelinux.cfg/boot:

# cat pxelinux.cfg/boot
default menu.c32
prompt 0

LABEL boot_local
        menu label ^Boot Local System
        menu default
        localboot 0
        timeout 50

LABEL boot_san
        menu label Boot ^Storage Area Network
        com32 syslinux/gpxecmd.c32
        append sanboot iscsi:<iscsi-host>::::iqn.example.com:win7

LABEL WINDOWS_PE
        menu label ^Windows Preinstallation Exnvironment
        kernel windows.pe/pxeboot.0

Both SanBoot and Window PE image works with Dell Vostro notebook now.

WAIK: Add Microsoft iSCSI service to WinPE

Microsoft iSCSI service allow user to connect to iSCSI target on SAN device. The default WINPE image doesn’t support iSCSI service. This topic shows how to add iSCSI service to WinPE image. Once added, you may connect to iSCSI target after boot into WinPE environment.

Add iSCSI service files to WinPE image

Start WAIK deployment Tools command prompt in privilege mode
Mount an WinPE image file in RW mode:
```
imagex /mountrw winpe.wim 1 mount
```

Copy the following files into mounted winpe’s “<mount>\windows\system32” folder:

Windows\System32\iscsicli.exe
Windows\System32\iscsicpl.exe
Windows\System32\iscsicpl.dll
Windows\System32\iscsidsc.dll
Windows\System32\iscsied.dll
Windows\System32\iscsiexe.dll
Windows\System32\iscsilog.dll
Windows\System32\iscsium.dll
Windows\System32\iscsiwmi.dll
Windows\System32\Drivers\msiscsi.sys
Windows\System32\en-us\iscsicli.exe.mui
Windows\System32\en-us\iscsicpl.dll.mui
Windows\System32\en-us\iscsicpl.exe.mui
Windows\System32\en-us\iscsidsc.dll.mui
Windows\System32\en-us\iscsiexe.dll.mui
Windows\System32\en-us\iscsilog.dll.mui

Update WinPE registry hive

Start RegEdit.exe in privilege mode
Select “HKEY_LOCAL_MACHINE”, and click File | Load Hive… to load hive file: <mount>\windows\system32\config\SYSTEM. Use PE_Sys as hive key name.
Select “HKEY_LOCAL_MACHINE”, and click File | Load Hive… to load hive file: <mount>\windows\system32\config\SOFTWARE. Use PE_Soft as hive key name.
The HKEY_LOCAL_MACHINE should have 2 hive loaded as follow:

Create a iscsi.reg file with the following content:

Windows Registry Editor Version 5.00
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\Svchost]
"Godzilla"=hex(7):4d,00,53,00,69,00,53,00,43,00,53,00,49,00,00,00,00,00
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\iSCSI]
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\iSCSI\Discovery]
"AllowiSNSFirewallException"=dword:00000001
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\iSCSI\Discovery\Authentication Cache]
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\iSCSI\Discovery\Send Targets]
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\iSCSI\Discovery\Static Targets]
 
[HKEY_LOCAL_MACHINE\PE_Soft\Microsoft\Windows NT\CurrentVersion\iSCSI\Discovery\Tunnel Address]
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\LEGACY_MSISCSI]
"NextInstance"=dword:00000001
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\LEGACY_MSISCSI\0000]
"Service"="MSiSCSI"
"Legacy"=dword:00000001
"ConfigFlags"=dword:00000000
"Class"="LegacyDriver"
"ClassGUID"="{8ECC055D-047F-11D1-A537-0000F8753ED1}"
"DeviceDesc"="@%SystemRoot%\\system32\\iscsidsc.dll,-5000"
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\ISCSIPRT]
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\ISCSIPRT\0000]
"ClassGUID"="{4d36e97b-e325-11ce-bfc1-08002be10318}"
"Class"="SCSIAdapter"
"HardwareID"=hex(7):52,00,4f,00,4f,00,54,00,5c,00,69,00,53,00,43,00,53,00,49,\
  00,50,00,72,00,74,00,00,00,00,00
"ConfigFlags"=dword:00000000
"Driver"="{4d36e97b-e325-11ce-bfc1-08002be10318}\\0000"
"Mfg"="@iscsi.inf,%msft%;Microsoft"
"Service"="iScsiPrt"
"DeviceDesc"="@iscsi.inf,%iscsiprt%;Microsoft iSCSI Initiator"
"Capabilities"=dword:00000000
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\ISCSIPRT\0000\Device Parameters]
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\ISCSIPRT\0000\Device Parameters\StorPort]
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\ISCSIPRT\0000\LogConf]
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Enum\Root\ISCSIPRT\0000\Control]
"ActiveService"="iScsiPrt"
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\iScsiPrt]
"DisplayName"="iScsiPort Driver"
"ImagePath"=hex(2):73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,44,00,\
  52,00,49,00,56,00,45,00,52,00,53,00,5c,00,6d,00,73,00,69,00,73,00,63,00,73,\
  00,69,00,2e,00,73,00,79,00,73,00,00,00
"ErrorControl"=dword:00000001
"Start"=dword:00000000
"Type"=dword:00000001
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\iScsiPrt\Parameters]
"BusType"=dword:00000009
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\iScsiPrt\Enum]
"0"="Root\\ISCSIPRT\\0000"
"Count"=dword:00000001
"NextInstance"=dword:00000001
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\MSiSCSI]
"DisplayName"="@%SystemRoot%\\system32\\iscsidsc.dll,-5000"
"Group"="iSCSI"
"ImagePath"=hex(2):25,00,73,00,79,00,73,00,74,00,65,00,6d,00,72,00,6f,00,6f,00,\
  74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,73,\
  00,76,00,63,00,68,00,6f,00,73,00,74,00,2e,00,65,00,78,00,65,00,20,00,2d,00,\
  6b,00,20,00,6e,00,65,00,74,00,73,00,76,00,63,00,73,00,00,00
"Description"="@%SystemRoot%\\system32\\iscsidsc.dll,-5001"
"ObjectName"="LocalSystem"
"ErrorControl"=dword:00000001
"Start"=dword:00000002
"Type"=dword:00000020
"ServiceSidType"=dword:00000001
"RequiredPrivileges"=hex(7):53,00,65,00,41,00,75,00,64,00,69,00,74,00,50,00,72,\
  00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,43,00,68,00,\
  61,00,6e,00,67,00,65,00,4e,00,6f,00,74,00,69,00,66,00,79,00,50,00,72,00,69,\
  00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,43,00,72,00,65,00,\
  61,00,74,00,65,00,47,00,6c,00,6f,00,62,00,61,00,6c,00,50,00,72,00,69,00,76,\
  00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,43,00,72,00,65,00,61,00,\
  74,00,65,00,50,00,65,00,72,00,6d,00,61,00,6e,00,65,00,6e,00,74,00,50,00,72,\
  00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,49,00,6d,00,\
  70,00,65,00,72,00,73,00,6f,00,6e,00,61,00,74,00,65,00,50,00,72,00,69,00,76,\
  00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,54,00,63,00,62,00,50,00,\
  72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,00,00
"FailureActionsOnNonCrashFailures"=dword:00000001
"FailureActions"=hex:50,46,00,00,01,00,00,00,01,00,00,00,03,00,00,00,14,00,00,\
  00,01,00,00,00,c0,d4,01,00,01,00,00,00,e0,93,04,00,00,00,00,00,00,00,00,00
"RebootMessage"="See Note 3 below"
"FailureCommand"="customScript.cmd"
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\MSiSCSI\Parameters]
"ServiceDll"=hex(2):25,00,73,00,79,00,73,00,74,00,65,00,6d,00,72,00,6f,00,6f,\
  00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,\
  69,00,73,00,63,00,73,00,69,00,65,00,78,00,65,00,2e,00,64,00,6c,00,6c,00,00,\
  00
"ServiceDllUnloadOnStop"=dword:00000001
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\MSiSCSI\Enum]
"0"="Root\\LEGACY_MSISCSI\\0000"
"Count"=dword:00000001
"NextInstance"=dword:00000001

[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Services\MSiSCSI]
"ImagePath"=hex(2):25,00,73,00,79,00,73,00,74,00,65,00,6d,00,72,00,6f,00,6f,00,\
  74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,73,\
  00,76,00,63,00,68,00,6f,00,73,00,74,00,2e,00,65,00,78,00,65,00,20,00,2d,00,\
  6b,00,20,00,47,00,6f,00,64,00,7a,00,69,00,6c,00,6c,00,61,00,00,00
 
Windows Registry Editor Version 5.00
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}]
"LegacyAdapterDetection"=dword:00000000
"Class"="SCSIAdapter"
"ClassDesc"="@%SystemRoot%\\System32\\SysClass.Dll,-3005"
@="@%SystemRoot%\\System32\\SysClass.Dll,-3005"
"IconPath"=hex(7):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,\
  74,00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,73,\
  00,65,00,74,00,75,00,70,00,61,00,70,00,69,00,2e,00,64,00,6c,00,6c,00,2c,00,\
  2d,00,31,00,30,00,00,00,00,00
"Installer32"="SysClass.Dll,ScsiClassInstaller"
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\0000]
"InfPath"="iscsi.inf"
"InfSection"="iScsiPort_Install_Control"
"ProviderName"="Microsoft"
"DriverDateData"=hex:00,80,8c,a3,c5,94,c6,01
"DriverDate"="6-21-2006"
"DriverVersion"="6.0.6000.16386"
"MatchingDeviceId"="root\\iscsiprt"
"DriverDesc"="Microsoft iSCSI Initiator"
"EnumPropPages32"="iscsipp.dll,iSCSIPropPageProvider"
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\0000\Parameters]
"TCPConnectTime"=dword:0000000f
"TCPDisconnectTime"=dword:0000000f
"WMIRequestTimeout"=dword:0000001e
"DelayBetweenReconnect"=dword:00000005
"MaxPendingRequests"=dword:000000ff
"EnableNOPOut"=dword:00000000
"MaxTransferLength"=dword:00040000
"MaxBurstLength"=dword:00040000
"FirstBurstLength"=dword:00010000
"MaxRecvDataSegmentLength"=dword:00010000
"MaxConnectionRetries"=dword:ffffffff
"MaxRequestHoldTime"=dword:0000003c
"LinkDownTime"=dword:0000000f
"IPSecConfigTimeout"=dword:0000003c
"InitialR2T"=dword:00000000
"ImmediateData"=dword:00000001
"ErrorRecoveryLevel"=dword:00000002
"PortalRetryCount"=dword:00000005
"NetworkReadyRetryCount"=dword:0000000a
"SrbTimeoutDelta"=dword:0000000f
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\0000\PersistentTargets]
@=""
 
[HKEY_LOCAL_MACHINE\PE_Sys\ControlSet001\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\Properties]
"DeviceType"=dword:00000004
"DeviceCharacteristics"=dword:00000100
"Security"=hex:01,00,04,90,00,00,00,00,00,00,00,00,00,00,00,00,14,00,00,00,02,\
  00,34,00,02,00,00,00,00,00,14,00,ff,01,1f,10,01,01,00,00,00,00,00,05,12,00,\
  00,00,00,00,18,00,ff,01,1f,10,01,02,00,00,00,00,00,05,20,00,00,00,20,02,00,\
  00

Import iscsi.reg into registry. It should update both PE_Sys and PE_Soft hive.
Unload both PE_Sys and PE_Soft hive by using File | Unload Hive… in registry editor.
Unmount and commit the WinPE mount:
```
imagex /unmount /commit mount
```
The WinPE image file is now ready with iSCSI service.

Start iSCSI service in WinPE environment

Boot the WinPE image either by using ISO or PXE

To start iSCSI service:

X:\windows\system32>net start msiscsi
The Microsoft iSCSI Initiator Service service is starting.
The Microsoft iSCSI Initiator Service service was started successfully.

type iscsicpl to start iSCSI GUI windows:
The iSCSI initiator is now active to connect to iSCSI target.

Reference

WinPE v3.0 and Microsoft iSCSI Initiator. URL: http://www.gregorystrike.com/2010/01/08/winpe-v3-0-and-microsoft-iscsi-initiator/

PXELinux: Load menu other than default

When loading PXELinux via DHCP as specified in dhcp.conf:

filename "pxelinux.0";

Once PXELinux was loaded, it will look for configuration in the following order:

Client PC’s GUID
Client PC’s MAC Address
Client PC”s IP address
pxelinux.cfg/default

These searching order may reveal from /var/log/messages:

Nov 28 08:58:09 dolphin in.tftpd[24603]: RRQ from 192.168.0.181 filename gpxelinux.0
Nov 28 08:58:09 dolphin in.tftpd[24604]: RRQ from 192.168.0.181 filename pxelinux.cfg/0338a9f6-d2b1-11df-9ec1
-0013d4d9c9e8
Nov 28 08:58:09 dolphin in.tftpd[24605]: RRQ from 192.168.0.181 filename pxelinux.cfg/01-70-71-bc-a8-4f-43
Nov 28 08:58:09 dolphin in.tftpd[24606]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0A800B5
Nov 28 08:58:09 dolphin in.tftpd[24607]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0A800B
Nov 28 08:58:09 dolphin in.tftpd[24608]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0A800
Nov 28 08:58:09 dolphin in.tftpd[24609]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0A80
Nov 28 08:58:09 dolphin in.tftpd[24610]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0A8
Nov 28 08:58:09 dolphin in.tftpd[24611]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0A
Nov 28 08:58:09 dolphin in.tftpd[24612]: RRQ from 192.168.0.181 filename pxelinux.cfg/C0
Nov 28 08:58:09 dolphin in.tftpd[24613]: RRQ from 192.168.0.181 filename pxelinux.cfg/C
Nov 28 08:58:09 dolphin in.tftpd[24614]: RRQ from 192.168.0.181 filename pxelinux.cfg/default

In most situation, create a default configuration file works well. There are some situations where we want to force the pxelinux to load menu configuration file other than default.

Here is a DHCP configuration that force pxelinux to load menu pxelinux.cfg/boot:

option space pxelinux;
option pxelinux.magic code 208 = string;
option pxelinux.configfile code 209 = text;
option pxelinux.pathprefix code 210 = text;
option pxelinux.reboottime code 211 = unsigned integer 32;
 
site-option-space "pxelinux";
if exists dhcp-parameter-request-list {
  # Always send the PXELINUX options
  option dhcp-parameter-request-list = concat(option-dhcp-parameter-request-list, "208,209,210,211");
}
 
option pxelinux.configfile      "pxelinux.cfg/boot";
filename "pxelinux.0";

The DHCP option 209 is the option to specify PXELinux config file. Line 10 specify option additional parameters that will pass to dhcp client.

PXELinux: Boot ISO image from network

PXELinux’s memdisk module may boot ISO image from network. However, not all ISO file support network booting. It is worth to try if you need the boot ISO image via PXELinux.

The following example shows two configuration to boot WinPE and SeaTools ISO. The PXE supports iPXE/gPXE to allow HTTP loading of ISO file. You may use native TFTP protocol for file loading too.

label WinPE ISO
        kernel syslinux/memdisk
        append iso
        initrd http://<ip-address>/winpe7_x64.iso

label SeaTools
        menu label SeaTools for DOS v2.23
        kernel syslinux/memdisk
        append iso
        initrd http://<ip-address>/SeaToolsDOS223ALL.ISO

Monday, November 28, 2011

iPXE: iSCSI for Microsoft Windows

Prepare environment to install and boot from iSCSI target

Syslinux 3.86 is the last known working version that may work with gpxe/ipxe. Prepare a TFTP boot folder as following:

# tree
.
├── pxelinux.cfg
│   └── default
├── syslinux -> syslinux.386
├── syslinux.386
│   ├── advdump.c32
│   ├── c32echo.c32
│   ├── cat.c32
│   ├── chain.c32
│   ├── cmd.c32
│   ├── comecho.com
│   ├── complex.c32
│   ├── config.c32
│   ├── copybs.com
│   ├── cpuid.c32
│   ├── cpuidtest.c32
│   ├── disk.c32
│   ├── display.c32
│   ├── dmitest.c32
│   ├── elf.c32
│   ├── entrydump.c32
│   ├── ethersel.c32
│   ├── fancyhello.c32
│   ├── fd.c32
│   ├── filetest.c32
│   ├── gfxboot.c32
│   ├── gfxboot.com
│   ├── gpxecmd.c32
│   ├── gpxelinux.0
│   ├── hdt.c32
│   ├── hello2.c32
│   ├── hello.c32
│   ├── ifcpu64.c32
│   ├── ifcpu.c32
│   ├── int18.com
│   ├── kbdmap.c32
│   ├── keytest.c32
│   ├── linux.c32
│   ├── localboot.c32
│   ├── mboot.c32
│   ├── mdiskchk.com
│   ├── memdump.com
│   ├── meminfo.c32
│   ├── menu.c32
│   ├── pcitest.c32
│   ├── pmload.c32
│   ├── poweroff.com
│   ├── pxechain.com
│   ├── pxelinux.0
│   ├── reboot.c32
│   ├── resolv.c32
│   ├── rosh.c32
│   ├── sanboot.c32
│   ├── sdi.c32
│   ├── serialinfo.c32
│   ├── simple.c32
│   ├── sysdump.c32
│   ├── syslinux.com
│   ├── test2.c32
│   ├── test.c32
│   ├── vesainfo.c32
│   ├── vesamenu.c32
│   └── vpdtest.c32
├── undionly.0 -> undionly.kpxe
├── undionly.kpxe
└── windows.pe
    ├── BCD
    ├── bootmgr.exe
    ├── boot.sdi
    ├── fonts
    │   ├── chs_boot.ttf
    │   ├── cht_boot.ttf
    │   ├── jpn_boot.ttf
    │   ├── kor_boot.ttf
    │   └── wgl4_boot.ttf
    ├── pxeboot.0 -> pxeboot.n12
    ├── pxeboot.n12
    ├── vista_x64.wim
    ├── vista_x86.wim
    ├── win7_x64.wim
    └── win7_x86.wim

Update /etc/dhcp/dhcpd.conf to use gpxelinux.0
```
filename "gpxelinux.0";
```

Restart dhcpd service

# service dhcpd restart
Shutting down dhcpd:                                       [  OK  ]
Starting dhcpd:                                            [  OK  ]

Update pxelinux.cfg/default:

LABEL boot_san
        menu label Boot ^Storage Area Network
        menu indent 5
        com32 syslinux/gpxecmd.c32
        append chain tftp://boot.example.com/sanboot.gpxe

label undionly
        menu label Boot iPXE UNDI
        menu indent 5
        kernel undionly.0

Create a sanboot.gpxe script file:

# cat sanboot.gpxe
#!gpxe

login
chain tftp://boot.example.com/syslinux/menu.c32 http://${username}:${password}@boot.example.com/~${username}/menu.cfg

A sample menu.cfg file:

UI syslinux/vesamenu.c32

LABEL Windows 7 x64
        com32 cmd.c32
        append sanboot iscsi:nas.example.com::::iqn.example.com:win7-x64

LABEL Windows 8 x64
        com32 cmd.c32
        append sanboot iscsi:nas.example.com::::iqn.example.com:win8-x64

Install Windows 7 on iSCSI target

Boot machine into iPXE kernel (Boot iPXE UNDI or undionly.0)
Press Ctrl-B to start iPXE command line
Obtain an IP address from dhcp
```
iPXE> dhcp net0
```
Preserve SAN device
```
iPXE> set keep-san 1
```
Supply chap information if necessary:
```
iPXE> login
```

Initialize iSCSI target:

iPXE> sanboot iscsi:nas.example.com::::iqn.2011-03.example.com:my-iscsi
Registered SAN device 0x80
Booting from SAN device 0x80
Boot from SAN device 0x80 failed: Operation canceled (http://ipxe.org/0x8080a0)
Preserving SAN device 0x80

Chain boot to Windows PE:

iPXE> chain tftp://boot.example.com/windows.pe/pxeboot.0

Or chain boot to Windows PE ISO:

iPXE> kernel syslinux/memdisk iso
iPXE> initrd http://<ip-address>/winpe7_x64.iso
iPXE> boot

Once boot into Windows PE, you may use the iSCSI target just like your local storage. You may install a Windows OS into the iSCSI target directly.

Boot from iSCSI target using iPXE

Boot machine into iPXE kernel
Press Ctrl-B to start iPXE command line
Obtain an IP address from DHCP
```
iPXE> dhcp net0
```
Supply chap information if necessary:
```
iPXE> login
```

Boot from iSCSI target:

iPXE> sanboot iscsi:nas.example.com::::iqn.2011-03.example.com:my-iscsi

Boot from iSCSI using PXE using HTTP

Boot from PXE
Use the pxe menu configuration to boot iSCSI target introduced in section “Prepare environment to install and boot from iSCSI target”

Reference

User-specific boot menus. URL: http://etherboot.org/wiki/appnotes/authmenus
Installing Windows Server 2008 to an iSCSI target. URL: http://etherboot.org/wiki/sanboot/win2k8_iscsi_install