From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keith Owens Date: Wed, 27 Sep 2006 02:45:50 +0000 Subject: Re: KDB blindly reads keyboard port Message-Id: <5239.1159325150@kao2.melbourne.sgi.com> List-Id: In-Reply-To: Your message of "Tue, 26 Sep 2006 13:54:30 CST." <200609261354.30722.bjorn.helgaas@hp.com> References: <200609261354.30722.bjorn.helgaas@hp.com> In-Reply-To: <200609261354.30722.bjorn.helgaas@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Bjorn Helgaas Cc: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org 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. No support for legacy I/O ports could be a bigger problem than just KDB. To fix just KDB, apply this patch over kdb-v4.4-2.6.18-common-1 and add 'kdb_skip_keyboard' to the boot command line on the offending hardware. --- arch/ia64/kdb/kdba_io.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) Index: linux/arch/ia64/kdb/kdba_io.c =================================--- linux.orig/arch/ia64/kdb/kdba_io.c +++ linux/arch/ia64/kdb/kdba_io.c @@ -38,6 +38,7 @@ #else #undef KDB_BLINK_LED #endif +static int kdb_skip_keyboard; #ifdef CONFIG_KDB_USB struct kdb_usb_exchange kdb_usb_infos; @@ -334,7 +335,8 @@ static int get_kbd_char(void) if (kbd_exists = 0) return -1; - if (inb(KBD_STATUS_REG) = 0xff && inb(KBD_DATA_REG) = 0xff) { + if (kdb_skip_keyboard || + (inb(KBD_STATUS_REG) = 0xff && inb(KBD_DATA_REG) = 0xff)) { kbd_exists = 0; return -1; } @@ -561,3 +563,14 @@ get_char_func poll_funcs[] = { void kdba_local_arch_setup(void) {} void kdba_local_arch_cleanup(void) {} + +/* Some hardware gets an MCA instead of returning 0xff when we read + * KBD_STATUS_REG. If these systems boot a kernel with CONFIG_VT=y then they + * need to add 'kdb_skip_keyboard' to the boot line. + */ +static int __init kdb_skip_keyboard_setup(char * str) +{ + kdb_skip_keyboard = 1; + return 1; +} +__setup("kdb_skip_keyboard", kdb_skip_keyboard_setup);