[gPXE] Machines hangs when exiting from CLI

[Michael Brown]

On Thursday 01 April 2010 15:42:53 Itay Gazit wrote:
> Are you sure we can't find a fix for those problematic BIOSes which can't
> continue after returning from protected mode?
>
> As you said expansion cards use this to provide a configuration menu
> prompt. This is exactly what I am willing to use gPXE, add CLI options to
> configure the card/gPXE.

Typically, expansion ROMs will force a reboot after leaving the POST-time 
configuration menu, presumably in order to avoid this exact problem.  gPXE 
could quite easily do this too.

Btw, did you know that gPXE already has CLI options to configure the card?

> Do you happen to have gPXE assembly reference code on how to call real mode
> C functions? I would like to start dealing with it!

If you mean calling real-mode functions from within gPXE, then look for uses 
of REAL_CODE().  This is not, however, related to the problem of staying in 
real mode.

gPXE did at one time support a build option called KEEP_IT_REAL, which allowed 
the whole stack to run in real mode.  However, this hasn't been functional 
for a while, and comes with some rather severe architectural limitations: in 
particular, real-mode operation is limited to 64kB of (uncompressed) code and 
64kB of data+stack.

Michael