ACPI: Remove ACPI_CUSTOM_DSDT_INITRD option

This essentially reverts commit 71fc47a9adf8ee89e5c96a47222915c5485ac437
("ACPI: basic initramfs DSDT override support"), because the code simply
isn't ready.

It did ugly things to the init sequence to populate the rootfs image
early, but that just ended up showing other problems with the whole
approach. The fact is, the VFS layer simply isn't initialized this
early, and the relevant ACPI code should either run much later, or this
shouldn't be done at all.

For 2.6.25, we'll just pick the latter option. We can revisit this
concept later if necessary.

Cc: Dave Hansen <[e-mail]>
Cc: Tilman Schmidt <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Thomas Renninger <[e-mail]>
Cc: Eric Piel <[e-mail]>
Cc: Len Brown <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Markus Gaugusch <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/acpi/dsdt-override.txt

···
-Linux supports two methods of overriding the BIOS DSDT:
+Linux supports a method of overriding the BIOS DSDT:
 
 CONFIG_ACPI_CUSTOM_DSDT builds the image into the kernel.
 
-CONFIG_ACPI_CUSTOM_DSDT_INITRD adds the image to the initrd.
-
-When to use these methods is described in detail on the
+When to use this method 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.

Documentation/acpi/initramfs-add-dsdt.sh

···
-#!/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"
-

Documentation/kernel-parameters.txt

···
 
 	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"
 

drivers/acpi/Kconfig

···
 	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

drivers/acpi/osl.c

···
 #define	OSI_STRING_LENGTH_MAX 64	/* arbitrary */
 static char osi_additional_string[OSI_STRING_LENGTH_MAX];
 
-#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
-static int acpi_no_initrd_override;
-#endif
-
 /*
  * "Ode to _OSI(Linux)"
  *
···
 	return AE_OK;
 }
 
-#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
-static struct acpi_table_header *acpi_find_dsdt_initrd(void)
-{
-	struct file *firmware_file;
-	mm_segment_t oldfs;
-	unsigned long len, len2;
-	struct acpi_table_header *dsdt_buffer, *ret = NULL;
-	struct kstat stat;
-	char *ramfs_dsdt_name = "/DSDT.aml";
-
-	printk(KERN_INFO PREFIX "Checking initramfs for custom DSDT\n");
-
-	/*
-	 * Never do this at home, only the user-space is allowed to open a file.
-	 * The clean way would be to use the firmware loader.
-	 * But this code must be run before there is any userspace available.
-	 * A static/init firmware infrastructure doesn't exist yet...
-	 */
-	if (vfs_stat(ramfs_dsdt_name, &stat) < 0)
-		return ret;
-
-	len = stat.size;
-	/* check especially against empty files */
-	if (len <= 4) {
-		printk(KERN_ERR PREFIX "Failed: DSDT only %lu bytes.\n", len);
-		return ret;
-	}
-
-	firmware_file = filp_open(ramfs_dsdt_name, O_RDONLY, 0);
-	if (IS_ERR(firmware_file)) {
-		printk(KERN_ERR PREFIX "Failed to open %s.\n", ramfs_dsdt_name);
-		return ret;
-	}
-
-	dsdt_buffer = kmalloc(len, GFP_ATOMIC);
-	if (!dsdt_buffer) {
-		printk(KERN_ERR PREFIX "Failed to allocate %lu bytes.\n", len);
-		goto err;
-	}
-
-	oldfs = get_fs();
-	set_fs(KERNEL_DS);
-	len2 = vfs_read(firmware_file, (char __user *)dsdt_buffer, len,
-		&firmware_file->f_pos);
-	set_fs(oldfs);
-	if (len2 < len) {
-		printk(KERN_ERR PREFIX "Failed to read %lu bytes from %s.\n",
-			len, ramfs_dsdt_name);
-		ACPI_FREE(dsdt_buffer);
-		goto err;
-	}
-
-	printk(KERN_INFO PREFIX "Found %lu byte DSDT in %s.\n",
-			len, ramfs_dsdt_name);
-	ret = dsdt_buffer;
-err:
-	filp_close(firmware_file, NULL);
-	return ret;
-}
-#endif
-
 acpi_status
 acpi_os_table_override(struct acpi_table_header * existing_table,
 		       struct acpi_table_header ** new_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",
···
 	}
 	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)
 {

init/initramfs.c

···
 	initrd_end = 0;
 }
 
-int __init populate_rootfs(void)
+static int __init populate_rootfs(void)
 {
 	char *err = unpack_to_rootfs(__initramfs_start,
 			 __initramfs_end - __initramfs_start, 0);
···
 	}
 	return 0;
 }
-#ifndef CONFIG_ACPI_CUSTOM_DSDT_INITRD
-/*
- * if this option is enabled, populate_rootfs() is called _earlier_ in the
- * boot sequence. This insures that the ACPI initialisation can find the file.
- */
 rootfs_initcall(populate_rootfs);
-#endif

init/main.c

···
 extern void tc_init(void);
 #endif
 
-#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
-extern int populate_rootfs(void);
-#else
-static inline void populate_rootfs(void) {}
-#endif
-
 enum system_states system_state;
 EXPORT_SYMBOL(system_state);
 
···
 
 	check_bugs();
 
-	populate_rootfs(); /* For DSDT override from initramfs */
 	acpi_early_init(); /* before LAPIC and SMP init */
 
 	/* Do the rest non-__init'ed, we're now alive */