Michael Hohmuth hohmuth at innocent.com
Mon Nov 23 21:25:12 CET 1998

Harald Fritzsche <Harald.Fritzsche at mpd.de> writes:

> I found (i hope so) the reason for the kbd: sig_sched: invalid
> ext_preempter in
> L4-Linux,  reported earlier.
> In file :
>     linux/arch/l4-i386/lib/task.c
> in function:
>     start_linux_server_thread()
> is used the variable
>     l4_threadid_t     foo_id
> uninitialized.
> I set foo_id to L4_INVALID_ID and the sig_sched disappears. But i don't
> if this is intended from the authors.

Your fix is correct.

The problem occurred because I forgot to commit some patches before
taking the snapshot.  I've appended the patches (which include your
fix) below.

[ from a different message: ]

> The function rs_init() hangs during boot (the boot stops for ever). Or a
> function after this part of initialization. The last what i see is:
> tty0* ... is a 16550A.
> If i disable the serial interface the boot goes on up to VFS mount and stops
> than.

This might be because the kernel debugger stub grabs irq 3 (the
interrupt for COM2).  Maybe Linux' serial driver waits for an
interrupt that never arrives because L4Linux cannot attach to irq3.

Configuring out the serial driver is the correct solution when using
a remote Gdb attached via a serial line.  If you don't have a remote
Gdb, try booting with the "-nokdb" kernel option and see if the
problem goes away.

hohmuth at innocent.com, hohmuth at inf.tu-dresden.de

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