Date: Wed, 19 Mar 2008 23:00:04 +0100 Subject: [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 v0.9b: Declare more functions __init by Jan Beulich v0.9c: Allow root to be / instead of nothing, bug reported by Robert Hampovcan Signed-off-by: Eric Piel --- 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 | 89 ++++++++++++++++++++++++++++++ 6 files changed, 180 insertions(+), 2 deletions(-) create mode 100644 Documentation/acpi/initramfs-add-dsdt.sh diff --git a/Documentation/acpi/dsdt-override.txt b/Documentation/acpi/dsdt-override.txt index febbb1b..5008f25 100644 --- 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. diff --git a/Documentation/acpi/initramfs-add-dsdt.sh b/Documentation/acpi/initramfs-add-dsdt.sh new file mode 100644 index 0000000..17ef6e8 --- /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" + diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index e07c432..6849df2 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -172,6 +172,9 @@ and is between 256 and 4096 characters. It is defined in the file 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" diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index c52fca8..8df213e 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -303,6 +303,17 @@ 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 diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index 235a138..c75f285 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -96,6 +96,11 @@ 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 + /* * "Ode to _OSI(Linux)" * @@ -338,6 +343,16 @@ acpi_os_table_override(struct acpi_table_header * existing_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", @@ -348,6 +363,15 @@ acpi_os_table_override(struct acpi_table_header * existing_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; diff --git a/init/initramfs.c b/init/initramfs.c index 8eeeccb..84f9a01 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -6,6 +6,9 @@ #include #include #include +#ifdef ACPI_CONFIG +#include +#endif static __initdata char *message; static void __init error(char *x) @@ -90,6 +93,12 @@ static __initdata unsigned long body_len, name_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; +#else +const char *file_looked_for = NULL; +#endif static void __init parse_header(char *s) { @@ -123,6 +132,7 @@ static __initdata enum state { SkipIt, GotName, CopyFile, + CopyFileMem, GotSymlink, Reset } state, next_state; @@ -259,6 +269,54 @@ static void __init clean_path(char *path, mode_t mode) 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; @@ -267,6 +325,8 @@ static int __init do_name(void) free_hash(); return 0; } + if (is_file_looked_for(file_looked_for)) + state = CopyFileMem; if (dry_run) return 0; clean_path(collected, mode); @@ -333,6 +393,7 @@ static __initdata int (*actions[])(void) = { [SkipIt] = do_skip, [GotName] = do_name, [CopyFile] = do_copy, + [CopyFileMem] = do_copy_mem, [GotSymlink] = do_symlink, [Reset] = do_reset, }; @@ -578,3 +639,31 @@ 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; + file_looked_for = ramfs_dsdt_name; + err = unpack_to_rootfs((char *)initrd_start, + initrd_end - initrd_start, 1); + file_looked_for = NULL; + + 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: Aborded 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 -- 1.5.6.4