From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Kdump broken in ACPI initialization upon reading SCI_EN bit Date: Thu, 19 Oct 2006 16:14:05 -0400 Message-ID: <20061019201405.GA15078@in.ibm.com> Reply-To: vgoyal@in.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from e4.ny.us.ibm.com ([32.97.182.144]:10178 "EHLO e4.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1946435AbWJSURl (ORCPT ); Thu, 19 Oct 2006 16:17:41 -0400 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e4.ny.us.ibm.com (8.13.8/8.12.11) with ESMTP id k9JKHerm024805 for ; Thu, 19 Oct 2006 16:17:40 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay02.pok.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id k9JKHeiW284340 for ; Thu, 19 Oct 2006 16:17:40 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id k9JKHeuh007647 for ; Thu, 19 Oct 2006 16:17:40 -0400 Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: linux-acpi@vger.kernel.org Cc: Fastboot mailing list Hi, On one of my machines (Intel Xeon 2.00GHz), Kdump is broken. Second kernel hangs during boot during ACPI initialization. I am using 2.6.19-rc2. It basically hangs when it tries to read from hardware whether system is already in ACPI mode or not. It tries to read SCI_ENABLE bit from PM1 control register. Interestingly this phenomenon is observed only if the code is running on a non-boot cpu (cpu id is not zero). I system crashes on cpu 0 and second kernel is booting on cpu 0 then everything is fine. Following is the code sequence. acpi_early_init() acpi_enable_subsystem() acpi_hw_get_mode acpi_hw_get_register acpi_hw_register_read acpi_hw_low_level_read acpi_os_read_port() In acpi_os_read_port() it tries to read port 0x804 (inw()) and then it hangs. Any idea what's happening? Are there any dependencies of this port being read by a boot cpu only? Any suggestions how can I debug further? Thanks Vivek