GDB doesn't display thread_id while debugging a core file

[Icarus Sparry]

Last November there was some discussion on this topic, which ended with
Daniel Jacobowitz saying in

http://sourceware.org/ml/gdb/2007-08/msg00068.html

	If we assume that the host's libthread_db will either recognize
the
	core file and do the right thing, or reject the core file, then
we can
	write a small target layer that uses it on top of corelow.c in a
	similar way to how linux-thread-db.c / proc-service.c use
linux-nat.c.

	It's just a matter of testing that on a couple of different
setups,
	like LinuxThreads and cross debuggers, to see how it behaves.
Or
	doesn't behave.


Being able to access variables declared with __thread in core files
would certainly be useful. Could someone give some reasonable guess of
the amount of effort required to do this? In particular for a powerpc32
corefile from a linux process with NPTL being debugged on an x86 linux
box.

Thanks.