linux-kernel - Re: KDB blindly reads keyboard port

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Message-ID: <14134.1163132600@kao2.melbourne.sgi.com>
Date:	Fri, 10 Nov 2006 15:23:20 +1100
From:	Keith Owens <kaos@....com>
To:	Bjorn Helgaas <bjorn.helgaas@...com>
cc:	linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org
Subject: Re: KDB blindly reads keyboard port 

Bjorn Helgaas (on Tue, 26 Sep 2006 13:54:30 -0600) wrote:
>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.

Bjron, could you try kdb-v4.4-2.6.19-rc5-{common,ia64}-2 on your
problem system?  I changed kdb so it only uses the keyboard if at least
one console matches the pattern /^tty[0-9]*$/.  IOW, if the user
specifies an i8042 style console on the command line (or uses the
default with CONFIG_VT=y) then kdb will attempt to use that keyboard.
Otherwise kdb ignores a VT style console, even when the kernel is
compiled with CONFIG_VT=y.

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