Ah! I finally have a progress bar that doesn't stall the build!
- pipe size in Linux is only 8*512=4096 bytes
- pipe size is not setable
- when the feeding process spits out data faster than the eating
process can read it, then the feeding process stalls after 4KiB
of data sent to the pipe
- for us, the progress bar would spawn a sub-shell every line,
and the sub-shell would in turn spawn a 'date' command.
Which was sloooww as hell, and would cause some kind of a
starvation: the pipe was full most of the time, and the
feeding process was stalled all this time.

Now, we use internal variables and a little hack based onan offset
to determine the elapsed time. Much faster this way, but still
CPU-intensive.

Status: committed upstream after 6.3.  Fixes some terminal mangling in

gdbtui.

2004-12-04  Daniel Jacobowitz  <dan@debian.org>

	PR tui/1703

	* linux-nat.c (linux_tracefork_child): Use _exit instead of exit.

	Suggested by Joshua Neuheisel.

Index: gdb-6.3/gdb/linux-nat.c

===================================================================

--- gdb-6.3.orig/gdb/linux-nat.c	2004-12-08 18:22:04.996973094 -0500

+++ gdb-6.3/gdb/linux-nat.c	2004-12-08 18:22:20.386956067 -0500

@@ -147,7 +147,7 @@ linux_tracefork_child (void)

   ptrace (PTRACE_TRACEME, 0, 0, 0);

   kill (getpid (), SIGSTOP);

   fork ();

-  exit (0);

+  _exit (0);

 }

 /* Wrapper function for waitpid which handles EINTR.  */