DSDT in initrd patch v0.3

@@ -36,6 +36,8 @@
 #include <asm/io.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi.h>
+#include <linux/init.h>
+#include <linux/vmalloc.h>

 #ifdef CONFIG_ACPI_EFI
 #include <linux/efi.h>

@@ -222,14 +224,59 @@
 	return AE_OK;
 }

+
+#ifdef CONFIG_ACPI_INITRD
+unsigned char* get_dsdt_from_initrd(unsigned char *start, unsigned char *end)
+{
+	unsigned char *data;
+	unsigned char signature[] = "INITRDDSDT123DSDT123";
+
+	if (start == NULL)
+		return NULL;
+	printk(KERN_INFO "Looking for DSDT in initrd ...");
+	if (!memcmp(start, "DSDT", 4)) {
+		printk(" found at beginning!\n");
+		return start;
+	}
+	end-=sizeof(signature)+5; /* don't scan above end, signature+\0+DSDT */
+	for (data=start; data < end ; ++data) {
+		if (!memcmp(data, signature, sizeof(signature)-1)) {
+			if (!memcmp(data+sizeof(signature), "DSDT", 4)) {
+				printk(" found (at offset %u)!\n", data+sizeof(signature)-start);
+				return data+sizeof(signature);
+			}
+		}
+	}
+	printk(" not found!\n");
+
+	return NULL;
+}
+#endif
+
+
 acpi_status
 acpi_os_table_override (struct acpi_table_header *existing_table,
 			struct acpi_table_header **new_table)
 {
+#ifdef CONFIG_ACPI_INITRD
+	extern unsigned long initrd_start, initrd_end;
+	unsigned char* new_dsdt=NULL;
+
+#endif
 	if (!existing_table || !new_table)
 		return AE_BAD_PARAMETER;

+#ifdef CONFIG_ACPI_INITRD
+	if (strncmp(existing_table->signature, "DSDT", 4) == 0 &&
+		(new_dsdt=get_dsdt_from_initrd((unsigned char*)initrd_start,
+			(unsigned char*)initrd_end)) != NULL)
+		*new_table = (struct acpi_table_header*)new_dsdt;
+	else
+		*new_table = NULL;
+#else
 	*new_table = NULL;
+#endif
+
 	return AE_OK;
 }

--- linux.orig/drivers/acpi/Config.in	2003-05-05 18:44:41.000000000 +0200
+++ linux/drivers/acpi/Config.in	2003-05-05 20:19:06.000000000 +0200

@@ -12,6 +12,10 @@
       bool         'CPU Enumeration Only' CONFIG_ACPI_HT_ONLY
     fi

+    if [ "$CONFIG_BLK_DEV_INITRD" = "y" ]; then
+      bool         'Read DSDT from initrd' CONFIG_ACPI_INITRD
+    fi
+
     if [ "$CONFIG_ACPI_HT_ONLY" = "y" ]; then
       define_bool CONFIG_ACPI_BOOT		y
     else
--- linux.orig/Documentation/Configure.help	2003-05-05 19:51:09.000000000 +0200
+++ linux/Documentation/Configure.help	2003-05-05 20:18:56.000000000 +0200

@@ -18602,6 +18602,14 @@
   handles PnP messages.  All ACPI devices use its services, so using
   them requires saying Y here.

+ACPI DSDT in initrd
+CONFIG_ACPI_INITRD
+	The DSDT (Differentiated System Description Table) often needs to be
+	overridden because of broken BIOS implementations. If you want to use
+	a customized DSDT, just copy it to /boot/initrd (which must be used as
+  initrd, of course). See http://gaugusch.at/kernel.shtml for instructions
+  on using an existing initrd with ACPI. If unsure, say N here.
+
 ACPI System Driver
 CONFIG_ACPI_SYS
   This driver will enable your system to shut down using ACPI, and


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