iPXE and SCCM 2012 Task Sequence

[SCCMDrivesmeNuts]

I'm in the midst of trying to figure out how I can stage WindowsPE to the local HD to kick off a task sequence rather than using software center in Windows. We noticed a paltry 50% success when trying to launch the TS this way from Windows XP.

We've had the most success tricking SCCM into thinking we're PXE booting, but have noticed that it eventually figured it out before launching the TS. My google searches led me to iPXE, where a number of people have claimed to get this working using iPXE and I'm wondering if someone can provide me with the following registry key so I can validate this myself.

HKLM\System\CurrentControlSet\Control

I know SSCM uses this to initially determine how the system was booted, but does eventually try and validate this after the fact. Any help is appreciated. Thanks

[mcb30]

(2014-05-05 14:00)SCCMDrivesmeNuts Wrote:  We've had the most success tricking SCCM into thinking we're PXE booting, but have noticed that it eventually figured it out before launching the TS. My google searches led me to iPXE, where a number of people have claimed to get this working using iPXE and I'm wondering if someone can provide me with the following registry key so I can validate this myself.

HKLM\System\CurrentControlSet\Control

I know SSCM uses this to initially determine how the system was booted, but does eventually try and validate this after the fact. Any help is appreciated. Thanks

I have worked through this problem. I don't have my notes to hand at present, but I can probably dig them out later.

Have you tried using http://ipxe.org/wimboot and the instructions at http://ipxe.org/howto/sccm? (Those instructions incorporate the registry hacks and other tricks used to get SCCM working with wimboot, which is going to be a very similar problem.)

Michael

[SCCMDrivesmeNuts]

(2014-05-05 16:09)mcb30 Wrote:  

(2014-05-05 14:00)SCCMDrivesmeNuts Wrote:  We've had the most success tricking SCCM into thinking we're PXE booting, but have noticed that it eventually figured it out before launching the TS. My google searches led me to iPXE, where a number of people have claimed to get this working using iPXE and I'm wondering if someone can provide me with the following registry key so I can validate this myself.

HKLM\System\CurrentControlSet\Control

I know SSCM uses this to initially determine how the system was booted, but does eventually try and validate this after the fact. Any help is appreciated. Thanks

I have worked through this problem. I don't have my notes to hand at present, but I can probably dig them out later.

Have you tried using http://ipxe.org/wimboot and the instructions at http://ipxe.org/howto/sccm? (Those instructions incorporate the registry hacks and other tricks used to get SCCM working with wimboot, which is going to be a very similar problem.)

Michael

That would be awesome if you could dig out your notes. We're in the process of running through setting up iPXE and have had challenges getting this to work in a virtual environment so we're trying to get some physical machines setup to test this out.

as an aside, I had opened up a case with Microsoft to see if this was possible and the answer we got from them was that it doesn't work this way and it's not a supported scenario.

[SCCMDrivesmeNuts]

Finally got iPXE working (we had to use an ISO) and even when changing PEBootType to RamDisk:OpticalDrive it's still failing to launch the task sequence. From the logs I can see that it's trying to resolve the path to the boot method we're trying to trick it to see and is failing to do so after 30 re-tries.

[mcb30]

(2014-05-06 18:09)SCCMDrivesmeNuts Wrote:  Finally got iPXE working (we had to use an ISO) and even when changing PEBootType to RamDisk:OpticalDrive it's still failing to launch the task sequence. From the logs I can see that it's trying to resolve the path to the boot method we're trying to trick it to see and is failing to do so after 30 re-tries.

Has your SCCM boot.wim file been modified exactly as per the instructions on http://ipxe.org/howto/sccm? (None of the steps on that page are optional; if any are missing then the result will not work.)

Michael

[mcb30]

(2014-05-06 22:18)mcb30 Wrote:  Has your SCCM boot.wim file been modified exactly as per the instructions on http://ipxe.org/howto/sccm? (None of the steps on that page are optional; if any are missing then the result will not work.)

I've looked over my notes. There are parts of the SCCM codebase which do not correctly handle error conditions. In particular, there are places which do not check for NULL pointers being returned, and which will happily propagate such NULL pointers through to other code which, in turn, fails to sanity-check for NULL pointer values. You eventually get a crash in totally innocent-looking unrelated code because something random got trashed several thousand lines of code earlier in the boot sequence.

I tracked this down by copying windbg into the SCCM boot.wim and then debugging with the command-line debugger (cdb). (I think windbg itself wouldn't start due to large numbers of missing libraries, but cdb was quite happy.) I spent a lot of time debugging it and eventually came up with a precise set of steps to generate a wimboot-bootable SCCM image; the results are at http://ipxe.org/howto/sccm.

Michael