From mboxrd@z Thu Jan 1 00:00:00 1970 From: Magnus Christensson Subject: RSDP scan problem Date: Thu, 04 Mar 2004 16:47:16 +0100 Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Message-ID: <40474F84.4060102@virtutech.se> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org There seem to be a problem with the RSDP scan in at least a few different kernel versions. In the 2.6 version I looked at we have: ---- /* * Scan memory looking for the RSDP signature. First search EBDA (low * memory) paragraphs and then search upper memory (E0000-FFFFF). */ rsdp_phys = acpi_scan_rsdp (0, 0x400); if (!rsdp_phys) rsdp_phys = acpi_scan_rsdp (0xE0000, 0xFFFFF); ---- In a 2.4 version we have: ---- /* * Physical address is given */ /* * Region 1) Search EBDA (low memory) paragraphs */ rsdp = acpi_tb_scan_memory_for_rsdp(__va(LO_RSDP_WINDOW_BASE), LO_RSDP_WINDOW_SIZE); ---- Both versions claim to check the EBDA in the comments, but if I'm not mistaken they really check the lowest part of physical memory. The location of the EBDA varies between BIOSes (the real mode segment part can be found at 40:0E). M. ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click