diff -urpN -X /home/eric/dontdiff linux-2.6.12-rc6.orig/Documentation/dsdt-initrd.txt linux-2.6.12-rc6/Documentation/dsdt-initrd.txt --- linux-2.6.12-rc6.orig/Documentation/dsdt-initrd.txt 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.12-rc6/Documentation/dsdt-initrd.txt 2005-06-12 10:54:37.000000000 +0200 @@ -0,0 +1,48 @@ +ACPI Custom DSDT read from initrd + +2003 by Markuss Gaugusch < dsdt at gaugusch dot org > +Special thanks go to Thomas Renninger from SuSE, who updated the patch for 2.6.0 +2004 maintained by Eric Piel < eric dot piel at tremplin-utc dot net > + +This option is intended for people who like to hack their DSDT and don't want +to recompile their kernel after every change. It can also be useful to distros +which offers pre-compiled kernels and want to allow their users to use a +modified DSDT. In the Kernel config, enable the ramdisk (not as module!) and initrd +(in Block Devices) and enable ACPI_CUSTOM_DSDT_INITRD at the ACPI +options (General Setup|ACPI Support|Read custom DSDT from initrd). + +A custom DSDT (Differentiated System Description Table) is useful when your +computer uses ACPI but problems occurs due to broken implementation. Typically, +your computer works but there are some troubles with the hardware detection or +the power management. You can check that troubles come from errors in the DSDT by +activating the ACPI debug option and reading the logs. This table is provided +by the BIOS, therefore it might be a good idea to check for BIOS update on your +vendor website before going any further. Errors are often caused by vendors +testing their hardware only with Windows or because there is code which is +executed only on a specific OS with a specific version and Linux hasn't been +considered during the development. + +Before you run away from customising your DSDT, you should note that already +corrected tables are available for a fair amount of computers on this web-page: +http://acpi.sf.net/dsdt . If you are part of the unluckies who cannot find +their hardware in this database, you can modify your DSDT by yourself. This +process is less painful than it sounds. Download the Intel ASL +compiler/decompiler at http://www.intel.com/technology/IAPC/acpi/downloads.htm . +As root, you then have to dump your DSDT and decompile it. By using the +compiler messages as well as the kernel ACPI debug messages and the reference book +(available at the Intel website and also at http://www.acpi.info), it is quite +easy to obtain a fully working table. + +Once your new DSDT is ready you'll have to add it to an initrd so that the +kernel can read the table at the very beginning of the boot. If you don't have +any initrd yet, you can just specify the table as an initrd file (in lilo or +grub) and it will work. Otherwise you have to separate the DSDT from the rest +by a signature. Do it like it: +echo -n "INITRDDSDT123DSDT123" >> /boot/initrd #magic signature +cat DSDT.aml >> /boot/initrd + +The message "Looking for DSDT in initrd..." will tell you if the DSDT was +found or not. If you need to update your DSDT, generate a new initrd and +perform the steps above. + + diff -urpN -X /home/eric/dontdiff linux-2.6.12-rc6.orig/drivers/acpi/Kconfig linux-2.6.12-rc6/drivers/acpi/Kconfig --- linux-2.6.12-rc6.orig/drivers/acpi/Kconfig 2005-06-12 10:51:51.000000000 +0200 +++ linux-2.6.12-rc6/drivers/acpi/Kconfig 2005-06-12 10:55:46.000000000 +0200 @@ -248,6 +248,22 @@ config ACPI_CUSTOM_DSDT_FILE help Enter the full path name to the file wich includes the AmlCode declaration. +config ACPI_CUSTOM_DSDT_INITRD + bool "Read Custom DSDT from initrd" + depends on X86 + depends on BLK_DEV_INITRD + default y + help + The DSDT (Differentiated System Description Table) often needs to be + overridden because of broken BIOS implementations. If you want to use + a customized DSDT, please use the mkinitrd tool (mkinitrd package) to + attach the DSDT to the initrd. For more details see + file: Documentation/dsdt-initrd.txt . If there is no table found in the + initrd, the DSDT from the BIOS is used. + + Even if you do not need a new one at the moment, you may want to use a + better implemented DSDT later. It is safe to say Y here. + config ACPI_BLACKLIST_YEAR int "Disable ACPI for systems before Jan 1st this year" depends on ACPI_INTERPRETER diff -urpN -X /home/eric/dontdiff linux-2.6.12-rc6.orig/drivers/acpi/osl.c linux-2.6.12-rc6/drivers/acpi/osl.c --- linux-2.6.12-rc6.orig/drivers/acpi/osl.c 2005-06-12 10:51:51.000000000 +0200 +++ linux-2.6.12-rc6/drivers/acpi/osl.c 2005-06-12 10:54:37.000000000 +0200 @@ -35,6 +35,7 @@ #include #include #include +#include #include #include #include @@ -246,6 +247,43 @@ acpi_os_predefined_override (const struc return AE_OK; } +#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD +struct acpi_table_header * acpi_find_dsdt_initrd(void) +{ + unsigned char start_signature[] = "INITRDDSDT123DSDT123"; + unsigned char *data = (unsigned char*)initrd_start; + unsigned char *dsdt_start = NULL; + + if (!initrd_start) + return NULL; + + printk(KERN_INFO PREFIX "Looking for DSDT in initrd..."); + if ((initrd_end - initrd_start) > 4 && + !strncmp((unsigned char*)initrd_start, "DSDT", 4)) + /* found DSDT at start of initrd */ + dsdt_start = (unsigned char*)initrd_start; + else { /* searching for start signature in initrd */ + for (; data < (unsigned char*)initrd_end; data++) { + if (!strncmp(data, start_signature, + sizeof(start_signature) - 1)) { + dsdt_start = data + sizeof(start_signature) - 1; + break; + } + } + } + /* check if head of dsdt is valid */ + if (dsdt_start && !strncmp(dsdt_start, "DSDT", 4)) { + printk(" found (at offset 0x%02x).\n", + (unsigned int) (dsdt_start - (unsigned char*)initrd_start)); + return (struct acpi_table_header*)dsdt_start; + } else + printk(" not found.\n"); + + /* no DSDT found */ + return NULL; +} +#endif + acpi_status acpi_os_table_override (struct acpi_table_header *existing_table, struct acpi_table_header **new_table) @@ -253,13 +291,18 @@ acpi_os_table_override (struct acpi_tabl if (!existing_table || !new_table) return AE_BAD_PARAMETER; + *new_table = NULL; + #ifdef CONFIG_ACPI_CUSTOM_DSDT if (strncmp(existing_table->signature, "DSDT", 4) == 0) *new_table = (struct acpi_table_header*)AmlCode; - else - *new_table = NULL; -#else - *new_table = NULL; +#endif +#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD + if (strncmp(existing_table->signature, "DSDT", 4) == 0) { + struct acpi_table_header* initrd_table = acpi_find_dsdt_initrd(); + if (initrd_table) + *new_table = initrd_table; + } #endif return AE_OK; }