path: root/patches/acpi-dsdt-2.6.30.patch

ACPI: initramfs DSDT override support

Permits to load of DSDT (the main ACPI table) from initramfs. In case this
option is selected, the initramfs is parsed at ACPI initialization (very early
boot time) to look for a file called "DSDT.aml". This aims at allowing users to
override the DSDT without recompiling the kernel.

Version 0.9 uses a different approach for reading the initramfs which avoids
using the filesystem infrastructure. It leverages the initramfs unpack code to find
and unpack the DSDT directly into the memory.

v0.9a: Fix compilation on non-ACPI platforms by René Rebe <rene@exactcode.de>
v0.9b: Declare more functions __init by Jan Beulich <jbeulich@novell.com>
v0.9c: Allow root to be / instead of nothing, bug reported by Robert Hampovcan

mandriva kernel version: diff is changed from patch present at
http://gaugusch.at/acpi-dsdt-initrd-patches/acpi-dsdt-initrd-v0.9c-2.6.28.patch
I adapted/fixed the patch for linux 2.6.30, and don't include acpi.h in
initramfs.c if ACPI_CUSTOM_DSDT_INITRD is disabled -- herton

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
---
 Documentation/acpi/dsdt-override.txt     |   12 +++
 Documentation/acpi/initramfs-add-dsdt.sh |   43 +++++++++++++
 Documentation/kernel-parameters.txt      |    3 
 drivers/acpi/Kconfig                     |   11 +++
 drivers/acpi/osl.c                       |   24 +++++++
 init/initramfs.c                         |   99 +++++++++++++++++++++++++++++++
 6 files changed, 190 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/acpi/initramfs-add-dsdt.sh

--- a/Documentation/acpi/dsdt-override.txt
+++ b/Documentation/acpi/dsdt-override.txt
@@ -1,7 +1,15 @@
-Linux supports a method of overriding the BIOS DSDT:
+Linux supports two methods of overriding the BIOS DSDT:
 
 CONFIG_ACPI_CUSTOM_DSDT builds the image into the kernel.
 
-When to use this method is described in detail on the
+CONFIG_ACPI_CUSTOM_DSDT_INITRD adds the image to the initrd.
+
+When to use these methods is described in detail on the
 Linux/ACPI home page:
 http://www.lesswatts.org/projects/acpi/overridingDSDT.php
+
+Note that if both options are used, the DSDT supplied
+by the INITRD method takes precedence.
+
+Documentation/initramfs-add-dsdt.sh is provided for convenience
+for use with the CONFIG_ACPI_CUSTOM_DSDT_INITRD method.
--- /dev/null
+++ b/Documentation/acpi/initramfs-add-dsdt.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+# Adds a DSDT file to the initrd (if it's an initramfs)
+# first argument is the name of archive
+# second argument is the name of the file to add
+# The file will be copied as /DSDT.aml
+
+# 20060126: fix "Premature end of file" with some old cpio (Roland Robic)
+# 20060205: this time it should really work
+
+# check the arguments
+if [ $# -ne 2 ]; then
+	program_name=$(basename $0)
+	echo "\
+$program_name: too few arguments
+Usage: $program_name initrd-name.img DSDT-to-add.aml
+Adds a DSDT file to an initrd (in initramfs format)
+
+  initrd-name.img: filename of the initrd in initramfs format
+  DSDT-to-add.aml: filename of the DSDT file to add
+  " 1>&2
+    exit 1
+fi
+
+# we should check it's an initramfs
+
+tempcpio=$(mktemp -d)
+# cleanup on exit, hangup, interrupt, quit, termination
+trap 'rm -rf $tempcpio' 0 1 2 3 15
+
+# extract the archive
+gunzip -c "$1" > "$tempcpio"/initramfs.cpio || exit 1
+
+# copy the DSDT file at the root of the directory so that we can call it "/DSDT.aml"
+cp -f "$2" "$tempcpio"/DSDT.aml
+
+# add the file
+cd "$tempcpio"
+(echo DSDT.aml | cpio --quiet -H newc -o -A -O "$tempcpio"/initramfs.cpio) || exit 1
+cd "$OLDPWD"
+
+# re-compress the archive
+gzip -c "$tempcpio"/initramfs.cpio > "$1"
+
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -216,6 +216,9 @@ and is between 256 and 4096 characters. 
 
 	acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT
 
+	acpi_no_initrd_override	[KNL,ACPI]
+			Disable loading custom ACPI tables from the initramfs
+
 	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
 			Format: To spoof as Windows 98: ="Microsoft Windows"
 
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -233,6 +233,17 @@ config ACPI_CUSTOM_DSDT
 	bool
 	default ACPI_CUSTOM_DSDT_FILE != ""
 
+config ACPI_CUSTOM_DSDT_INITRD
+	bool "Read Custom DSDT from initramfs"
+	depends on BLK_DEV_INITRD
+	default n
+	help
+	  This option supports a custom DSDT by optionally loading it from initrd.
+	  See Documentation/acpi/dsdt-override.txt
+
+	  If you are not using this feature now, but may use it later,
+	  it is safe to say Y here.
+
 config ACPI_BLACKLIST_YEAR
 	int "Disable ACPI for systems before Jan 1st this year" if X86_32
 	default 0
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -95,6 +95,11 @@ static DEFINE_SPINLOCK(acpi_res_lock);
 #define	OSI_STRING_LENGTH_MAX 64	/* arbitrary */
 static char osi_additional_string[OSI_STRING_LENGTH_MAX];
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+static __initdata int acpi_no_initrd_override;
+extern struct acpi_table_header *acpi_find_dsdt_initrd(void);
+#endif
+
 /*
  * The story of _OSI(Linux)
  *
@@ -334,6 +339,16 @@ acpi_os_table_override(struct acpi_table
 	if (strncmp(existing_table->signature, "DSDT", 4) == 0)
 		*new_table = (struct acpi_table_header *)AmlCode;
 #endif
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+	if ((strncmp(existing_table->signature, "DSDT", 4) == 0) &&
+	    !acpi_no_initrd_override) {
+		struct acpi_table_header *initrd_table;
+
+		initrd_table = acpi_find_dsdt_initrd();
+		if (initrd_table)
+			*new_table = initrd_table;
+	}
+#endif
 	if (*new_table != NULL) {
 		printk(KERN_WARNING PREFIX "Override [%4.4s-%8.8s], "
 			   "this is unsafe: tainting kernel\n",
@@ -344,6 +359,15 @@ acpi_os_table_override(struct acpi_table
 	return AE_OK;
 }
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+static int __init acpi_no_initrd_override_setup(char *s)
+{
+	acpi_no_initrd_override = 1;
+	return 1;
+}
+__setup("acpi_no_initrd_override", acpi_no_initrd_override_setup);
+#endif
+
 static irqreturn_t acpi_irq(int irq, void *dev_id)
 {
 	u32 handled;
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -8,6 +8,9 @@
 #include <linux/dirent.h>
 #include <linux/syscalls.h>
 #include <linux/utime.h>
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+#include <acpi/acpi.h>
+#endif
 
 static __initdata char *message;
 static void __init error(char *x)
@@ -125,6 +128,14 @@ static __initdata unsigned long body_len
 static __initdata uid_t uid;
 static __initdata gid_t gid;
 static __initdata unsigned rdev;
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+static __initdata char *file_looked_for;
+static __initdata struct acpi_table_header *file_mem;
+static __initdata int find_dsdt;
+#else
+const char *file_looked_for = NULL;
+const int find_dsdt = 0;
+#endif
 
 static void __init parse_header(char *s)
 {
@@ -159,6 +170,7 @@ static __initdata enum state {
 	SkipIt,
 	GotName,
 	CopyFile,
+	CopyFileMem,
 	GotSymlink,
 	Reset
 } state, next_state;
@@ -228,6 +240,10 @@ static int __init do_header(void)
 	parse_header(collected);
 	next_header = this_header + N_ALIGN(name_len) + body_len;
 	next_header = (next_header + 3) & ~3;
+	if (find_dsdt) {
+		read_into(name_buf, N_ALIGN(name_len), GotName);
+		return 0;
+	}
 	state = SkipIt;
 	if (name_len <= 0 || name_len > PATH_MAX)
 		return 0;
@@ -290,6 +306,54 @@ static void __init clean_path(char *path
 
 static __initdata int wfd;
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+static __init int is_file_looked_for(char *filename)
+{
+	char *tmp_collected = collected;
+	if (file_looked_for == NULL)
+		return 0;
+	if (!S_ISREG(mode))
+		return 0;
+	/* remove the leading / */
+	while (*tmp_collected == '/')
+		tmp_collected++;
+	return (strcmp(tmp_collected, file_looked_for) == 0);
+}
+
+static int __init do_copy_mem(void)
+{
+	static void *file_current; /* current position in the memory */
+	if (file_mem == NULL) {
+		if (body_len < 4) { /* check especially against empty files */
+			error("file is less than 4 bytes");
+			return 1;
+		}
+		file_mem = kmalloc(body_len, GFP_ATOMIC);
+		if (!file_mem) {
+			error("failed to allocate enough memory");
+			return 1;
+		}
+		file_current = file_mem;
+	}
+	if (count >= body_len) {
+		memcpy(file_current, victim, body_len);
+		eat(body_len);
+		file_looked_for = NULL; /* don't find files with same name */
+		state = SkipIt;
+		return 0;
+	} else {
+		memcpy(file_current, victim, count);
+		file_current += count;
+		body_len -= count;
+		eat(count);
+		return 1;
+	}
+}
+#else
+static inline int is_file_looked_for(char *filename) {return 0;}
+#define do_copy_mem NULL /* because it is used as a pointer */
+#endif
+
 static int __init do_name(void)
 {
 	state = SkipIt;
@@ -298,6 +362,10 @@ static int __init do_name(void)
 		free_hash();
 		return 0;
 	}
+	if (is_file_looked_for(file_looked_for))
+		state = CopyFileMem;
+	if (find_dsdt)
+		return 0;
 	clean_path(collected, mode);
 	if (S_ISREG(mode)) {
 		int ml = maybe_link();
@@ -370,6 +438,7 @@ static __initdata int (*actions[])(void)
 	[SkipIt]	= do_skip,
 	[GotName]	= do_name,
 	[CopyFile]	= do_copy,
+	[CopyFileMem]	= do_copy_mem,
 	[GotSymlink]	= do_symlink,
 	[Reset]		= do_reset,
 };
@@ -606,3 +675,33 @@ static int __init populate_rootfs(void)
 	return 0;
 }
 rootfs_initcall(populate_rootfs);
+
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+struct __init acpi_table_header *acpi_find_dsdt_initrd(void)
+{
+	char *err, *ramfs_dsdt_name = "DSDT.aml";
+
+	printk(KERN_INFO "ACPI: Checking initramfs for custom DSDT\n");
+	file_mem = NULL;
+	find_dsdt = 1;
+	file_looked_for = ramfs_dsdt_name;
+	err = unpack_to_rootfs((char *)initrd_start,
+			initrd_end - initrd_start);
+	file_looked_for = NULL;
+	find_dsdt = 0;
+
+	if (err) {
+		/*
+		 * Even if reading the DSDT file was successful,
+		 * we give up if the initramfs cannot be entirely read.
+		 */
+		kfree(file_mem);
+		printk(KERN_ERR "ACPI: Aborted because %s.\n", err);
+		return NULL;
+	}
+	if (file_mem)
+		printk(KERN_INFO "ACPI: Found DSDT in %s.\n", ramfs_dsdt_name);
+
+	return file_mem;
+}
+#endif
Fix to some problems in acpi-dsdt-initrd-v0.9c-2.6.28.patch:
* acpi_os_table_override isn't an __init function, so looks wrong it to
  reference an __initdata variable, remove __initdata annotation from
  acpi_no_initrd_override
* The __init annotation from acpi_find_dsdt_initrd wasn't being taken
  into account, as can be verified when building with
  CONFIG_DEBUG_SECTION_MISMATCH=y. Changing
  "struct __init acpi_table_header *acpi_find_dsdt_initrd(void)"
  to
  "struct acpi_table_header __init *acpi_find_dsdt_initrd(void)"
  would fix the problem, but then debug section mismatch checker would
  complain about non __init acpi_os_table_override using
  acpi_find_dsdt_initrd, and it's right. We can't annotate
  acpi_os_table_override with __init, thus change code to save the
  loaded dsdt from initrd into global acpi_dsdt_initrd.
* We must check for initrd_start before trying to load DSDT from initrd.

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
---
 drivers/acpi/osl.c |   13 ++++---------
 init/initramfs.c   |    7 ++++---
 init/main.c        |    7 +++++++
 3 files changed, 15 insertions(+), 12 deletions(-)

--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -96,8 +96,8 @@ static DEFINE_SPINLOCK(acpi_res_lock);
 static char osi_additional_string[OSI_STRING_LENGTH_MAX];
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
-static __initdata int acpi_no_initrd_override;
-extern struct acpi_table_header *acpi_find_dsdt_initrd(void);
+static int acpi_no_initrd_override;
+struct acpi_table_header *acpi_dsdt_initrd = NULL;
 #endif
 
 /*
@@ -341,13 +341,8 @@ acpi_os_table_override(struct acpi_table
 #endif
 #ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
 	if ((strncmp(existing_table->signature, "DSDT", 4) == 0) &&
-	    !acpi_no_initrd_override) {
-		struct acpi_table_header *initrd_table;
-
-		initrd_table = acpi_find_dsdt_initrd();
-		if (initrd_table)
-			*new_table = initrd_table;
-	}
+	    !acpi_no_initrd_override && acpi_dsdt_initrd)
+		*new_table = acpi_dsdt_initrd;
 #endif
 	if (*new_table != NULL) {
 		printk(KERN_WARNING PREFIX "Override [%4.4s-%8.8s], "
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -132,6 +132,7 @@ static __initdata unsigned rdev;
 static __initdata char *file_looked_for;
 static __initdata struct acpi_table_header *file_mem;
 static __initdata int find_dsdt;
+extern struct acpi_table_header *acpi_dsdt_initrd;
 #else
 const char *file_looked_for = NULL;
 const int find_dsdt = 0;
@@ -677,7 +678,7 @@ static int __init populate_rootfs(void)
 rootfs_initcall(populate_rootfs);
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
-struct __init acpi_table_header *acpi_find_dsdt_initrd(void)
+void __init acpi_find_dsdt_initrd(void)
 {
 	char *err, *ramfs_dsdt_name = "DSDT.aml";
 
@@ -697,11 +698,11 @@ struct __init acpi_table_header *acpi_fi
 		 */
 		kfree(file_mem);
 		printk(KERN_ERR "ACPI: Aborted because %s.\n", err);
-		return NULL;
+		return;
 	}
 	if (file_mem)
 		printk(KERN_INFO "ACPI: Found DSDT in %s.\n", ramfs_dsdt_name);
 
-	return file_mem;
+	acpi_dsdt_initrd = file_mem;
 }
 #endif
--- a/init/main.c
+++ b/init/main.c
@@ -91,6 +91,11 @@ extern void acpi_early_init(void);
 #else
 static inline void acpi_early_init(void) { }
 #endif
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+extern void acpi_find_dsdt_initrd(void);
+#else
+static inline void acpi_find_dsdt_initrd(void) { }
+#endif
 #ifndef CONFIG_DEBUG_RODATA
 static inline void mark_rodata_ro(void) { }
 #endif
@@ -692,6 +697,8 @@ asmlinkage void __init start_kernel(void
 
 	check_bugs();
 
+	if (initrd_start)
+		acpi_find_dsdt_initrd();
 	acpi_early_init(); /* before LAPIC and SMP init */
 
 	ftrace_init();