From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [parisc-linux] Console Kernel Panic Date: Tue, 20 Dec 2005 09:42:29 -0700 Message-ID: <20051220164229.GX2361@parisc-linux.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:27871 "EHLO palinux.hppa") by vger.kernel.org with ESMTP id S1751125AbVLTQmb (ORCPT ); Tue, 20 Dec 2005 11:42:31 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Keven Tipping Cc: parisc-linux@lists.parisc-linux.org, linux-serial@vger.kernel.org, Alan Cox On Mon, Dec 19, 2005 at 08:50:18PM -0700, Keven Tipping wrote: > I am currently running Kernel version 2.6.15-rc6-pa1. > > This problem, however, is evident in 2.6.14.3-pa0, and 2.6.15-rc5-pa5, as well as 2.6.12.2 (Gentoo 2005 LiveCD). Problem remains regardless of SMP or Uniprocessor kernels. > > On the K Class (it appears it is limited to these machines?), if nothing is currently running on the ttyB0 Serial Console, if you press any key, the system burps up the following: > > Kernel Panic: Kernel Fault > Not Syncing... > > What I mean by "nothing running" is if Agetty is NOT running, NOR is Bash. I really think you could have provided the useful bits from a kernel panic here. Please see http://www.parisc-linux.org/faq/kernelbug-howto.html However, I've reproduced it myself. Here's the relevant bits: IAOQ[0]: mux_read+0x4c/0x17c IAOQ[1]: mux_read+0x50/0x17c RP(r2): mux_poll+0x78/0x88 The instruction faulting is: 4c: 48 94 02 28 ldw 114(,r4),r20 which corresponds to the load of flip.count: if (tty->flip.count >= TTY_FLIPBUF_SIZE) continue; ie the 'tty' variable is NULL at this point. Alan, you seem to have the tarbaby for ttys at the moment ... any idea why port->info->tty would be NULL? The corresponding routine in 8250.c (receive_chars()) doesn't check for tty being NULL. So is there some non-obvious check the MUX driver is missing, or is this a latent problem in 8250 too?