From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Date: Tue, 26 Sep 2006 19:54:30 +0000 Subject: KDB blindly reads keyboard port Message-Id: <200609261354.30722.bjorn.helgaas@hp.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Keith Owens Cc: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org get_kbd_char() in arch/ia64/kdb/kdba_io.c does "inb(KBD_STATUS_REG)". But we don't know whether there's even an i8042 keyboard controller present. On HP ia64 boxes, there is no i8042, and trying to read from it can cause an MCA. This depends on the specific platform and how it is configured. I observed this MCA while booting the SLES10 install kernel on an HP rx7620 in "default" acpiconfig mode. The supported acpiconfig mode on this box is "single-pci-domain", which also puts some legacy ports into "soft-fail" mode, where the read will just return 0xff instead of causing an MCA. But I think it's wrong to blindly poke around in I/O port space. i8042_pnp_init() uses PNPACPI to figure out whether the i8042 device is present. That's probably too heavy-weight for what you want to do in KDB, though. Bjorn