[Patch] DSDT in initrd

[Patch] DSDT in initrd

[Markus Gaugusch]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1262 bytes --]

Hi,
I've implemented my patch to put the DSDT into the initial ramdisk.
It uses the same approach as bootsplash: just use the raw initrd data.

A "magic" signature ("INITRDDSDT123DSDT123") seperates the normal initrd
content from the DSDT. To use it, apply my patch (it's against 2.4.21-rc1
+ acpi-20030424) and do the following:
1.) enable CONFIG_BLK_DEV_INITRD and CONFIG_ACPI_INITRD
2.) recompile
3.) Create the initrd (or modify an existing)

echo "INITRDDSDT123DSDT123" >> /boot/initrd.dsdt
cat DSDT.aml >> /boot/initrd.dsdt

If you don't have an initrd yet, don't worry. Just perform the steps
above and everything will be fine. Don't forget to update your bootloader
(lilo needs this, grub not).

Then reboot.
The message "Looking for DSDT in initrd... found!" should be in your dmesg
after next boot. (for some reason <6> is before "found", but I'm sure
that someone will be able to give me the right pointers to fix that).

This is my first kernel patch, please be gentle :)
But I would really appreciate, if it was applied to official ACPI.

kind regards
Markus Gaugusch
-- 
__________________    /"\
Markus Gaugusch       \ /    ASCII Ribbon Campaign
markus-z+rTbpWsRgbk7+2FdBfRIA@public.gmane.org     X     Against HTML Mail
                      / \

[-- Attachment #2: Type: TEXT/PLAIN, Size: 2849 bytes --]

--- linux.orig/drivers/acpi/osl.c	2003-05-05 18:00:25.000000000 +0200
+++ linux/drivers/acpi/osl.c	2003-05-05 21:59:19.000000000 +0200
@@ -33,6 +33,10 @@
 #include <linux/interrupt.h>
 #include <linux/kmod.h>
 #include <linux/delay.h>
+#ifdef CONFIG_ACPI_INITRD
+#include <linux/init.h>
+#include <linux/vmalloc.h>
+#endif
 #include <asm/io.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi.h>
@@ -222,14 +226,52 @@
 	return AE_OK;
 }
 
+
+#ifdef CONFIG_ACPI_INITRD
+unsigned char signature[] = "INITRDDSDT123DSDT123";
+
+unsigned char* get_dsdt_from_initrd(unsigned char *start, unsigned char *end)
+{
+	unsigned char *data;
+
+	if (start == NULL)
+		return NULL;
+	printk(KERN_INFO "Looking for DSDT in initrd ...");
+	for (data=start; data < end ; ++data) {
+		if (!memcmp(data, signature, sizeof(signature)-1)) {
+			printk(KERN_INFO " found!");
+			return data+sizeof(signature);
+		}
+	}
+	printk(KERN_INFO " not found!");
+
+	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 +18602,13 @@
   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 a broken BIOS implementation. If you want to put
+  the overriden DSDT into the initrd, see http://gaugusch.at/kernel.shtml
+  for more info. If unsure, say N here.
+
 ACPI System Driver
 CONFIG_ACPI_SYS
   This driver will enable your system to shut down using ACPI, and

Re: [Patch] DSDT in initrd

[Sebastian Henschel]

[-- Attachment #1: Type: text/plain, Size: 1274 bytes --]

hi markus...

Received at 2003-05-06 / 09:02 by Markus Gaugusch:

> I've implemented my patch to put the DSDT into the initial ramdisk.
> It uses the same approach as bootsplash: just use the raw initrd data.

hey, it seems to work here. my ac_adapter is back with my custom DSDT
from the initrd.  :) thank you very much.

> 1.) enable CONFIG_BLK_DEV_INITRD and CONFIG_ACPI_INITRD

perhaps you should also say that the ramdisk support has to be
included statically (CONFIG_BLK_DEV_RAM=y). i had it as a module and was
looking for these options to no avail. :)

> Then reboot.
> The message "Looking for DSDT in initrd... found!" should be in your dmesg
> after next boot. (for some reason <6> is before "found", but I'm sure
> that someone will be able to give me the right pointers to fix that).

i do not know much about printk, but possibly, KERN_INFO (<6>) is only
parsed when it is at the beginning of a line. so your "found" or "not
found" statements would also be printed out with KERN_INFO as subsequent
calls of printk without a newline, although the do not start with
KERN_INFO. just a wild guess. :)

cheers,
 sebastian

-- 
::: sebastian henschel
::: kodeaffe
::: lynx -source http://www.kodeaffe.de/shensche.pub | gpg --import

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]