I'm trying to set up a set of Compaq EVO T20 40/64 thin clients in a 
LTSP-environment. I realize it might not be totally relevant on this 
list...this is a first post for me here so feel free to correct me if that is 
the case (wth some pointers on suitable lists would be great).

The T20 line is made for Windows NT Embedded (or CE on the lower-memory 
models). The challenge is to make them boot anything else than the provided 
NTe firmware. As long as I can get them to boot a Linux system at all I 
expect I shall be able to do the necesarry changes to have a permanent LTSP 
box.

The reason I think it can be done at all is that earlier posts on this list 
suggests that the T20s "work fine" (and also the Geode platform in general is 
said to work fine with Linux, from what little I've seen). Apparently the 
boot mechanisms must have been easier to intercept on those...

If anyone has pulled this off, I would be very grateful for a pointer on how 
to do this. I know it can be done theoretically, but how much hacking is 
involved?

What I've found so far:

Main problem is that it comes without PXE. And since it comes without CD or 
floppy all the usual ways of replacing the boot-code is unavailable. Booting 
into NTe doesn't help either: It comes with the possibility to start two 
different windows terminal clients and to shut down... not even change 
resolution, nothing. Changing settings in this environment is done through a 
server software solution that I don't have (and don't plan to acquire, using 
LTSP after all).

Before going further let me point you to 
http://h18007.www1.hp.com/support/files/ThinClients/us/locate/91_4970.html
, which has the firmware and firmware update tools (they extract nicely using 
WINE for inspection).

Possible attack points, and why they failed:

- Most important is the firmware updating mechanism. If you hold down "P" when 
the box boots it enters firmware update mode, where it does a DHCP/TFTP combo 
(on custom ports). What is downloaded through TFTP is a tagged binary (the 
tag includes execution start address and is partially documented in the 
firmware updater tool, see below). I tried tagging etherboot (with any 
network card, not important, just wanted to see the prompt of it), but after 
successful download nothing happened at all (a freeze, I guess). (In practice 
this process happens through the netxfer tool, which also contains the tagger 
program). (After I've gotten etherboot to run through this method I expect I 
shall be able to manually flash the memory from Linux and install etherboot 
permanently).

- There's a somewhat mysterious "NTe w/ PXE" firmware available for the 64/64 
version. It's marketed as a way of updating the firmware, but probably the 
PXE could be used against LTSP too. Unfortunately I have the 48/64 version. 
Tried putting a 128 MB smartmedia card in the expansion slot but the firmware 
still wouldn't upload (the upgrade program loaded on the client but that 
program failed with obscure references to a compaq signature or something, I 
can type down a screenshot if anyone's interested).

- The BIOS. The BIOS is made by WYSE and sits in a socket roughly a square 
centimeter (one side a little longer than the other), I don't know the name. 
Anyway I guess I could install it in another motherboard while that other 
motherboard is running and flash over the BIOS with a LinuxBIOS and etherboot 
combo. Even if I could then flash the memory and reuse the BIOS on the next 
client (rinse, repeat) I really wanted to check a mailing list before going 
into LinuxBIOS heavily.

So, if anyone either did this or have any pointers on getting etherboot to run 
through the update mechanism (we do, after all, have both a working image and 
the image we want to work...) then I'd be very grateful to hear from you.

// Dag Sverre



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