Hi,

I am trying to integrate binfmt_xout.c into kernel 2.4 as part of the 
linux-abi project (formerly known as iBCS). For old Xenix 286 binaries the 
lcall7 gate needs to part of the LDT.

In kernels 2.0 sys_modify_ldt(0,...) used to return the default_ldt (with 
lcall7 gate) if there were no segments set up. This behaviour changed in 
kernels 2.2 . As a result of a discussion with Linus, David Bruce wrote a 
patch for binfmt_xout.c tweaking with gdt and current->tss.ldt to get the
address of default_ldt. This patch does not work any more with kernels 2.4
as tss vanished from task_struct. 

I do see 4 ways to cope with this problem:

a) extend sys_modify_ldt with a function to retrieve the default_ldt. I did 
   this for testing (see attached diff for arch/i386/kernel/ldt.c ).

b) do some work an Davids patch but this is kind of magic for me :-)
   (see attached default_ldt patch)

c) loose the option to compile binfmt_xout (and the rest of linux-abi) as 
   module and simply use the symbol default_ldt. I dint't try that.

d) Forget about those old fashioned 286 binaries. This option will make some
   linux users feel sad, as they run these progs for their daily business.

Joerg
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Joerg Ahrens                                              _/           
Koenigsberger Strasse 32                                _/_/
31226 Peine                                           _/  _/
Tel.: 05171/57308                             _/    _/_/_/_/
e-mail: joerg@hydrops.han.de                _/_/_/_/      _/
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