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-rw-r--r--drivers/acpi/Kconfig17
-rw-r--r--drivers/acpi/osl.c73
2 files changed, 86 insertions, 4 deletions
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index ccf6ea95f68..0442ae153a2 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -274,6 +274,23 @@ config ACPI_CUSTOM_DSDT_FILE
Enter the full path name to the file which includes the AmlCode
declaration.
+config ACPI_CUSTOM_DSDT_INITRD
+ bool "Read Custom DSDT from initramfs"
+ depends on BLK_DEV_INITRD
+ default n
+ help
+ The DSDT (Differentiated System Description Table) often needs to be
+ overridden because of broken BIOS implementations. If this feature is
+ activated you will be able to provide a customized DSDT by adding it
+ to your initramfs. If your mkinitrd tool does not support this feature
+ a script is provided in the documentation. For more details see
+ <file:Documentation/dsdt-initrd.txt> or <http://gaugusch.at/kernel.shtml>.
+ If there is no table found, it will fall-back to the custom DSDT
+ in-kernel (if activated) or to the DSDT from the BIOS.
+
+ Even if you do not need a new one at the moment, you may want to use a
+ better DSDT 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 e53fb516f9d..131936e7ff1 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -312,6 +312,66 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val,
return AE_OK;
}
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+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 "Looking for DSDT in initramfs... ");
+
+ /*
+ * 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. So we need a static/init firmware
+ * infrastructure, which doesn't exist yet...
+ */
+ if (vfs_stat(ramfs_dsdt_name, &stat) < 0) {
+ printk("not found.\n");
+ return ret;
+ }
+
+ len = stat.size;
+ /* check especially against empty files */
+ if (len <= 4) {
+ printk("error, file is too small: only %lu bytes.\n", len);
+ return ret;
+ }
+
+ firmware_file = filp_open(ramfs_dsdt_name, O_RDONLY, 0);
+ if (IS_ERR(firmware_file)) {
+ printk("error, could not open file %s.\n", ramfs_dsdt_name);
+ return ret;
+ }
+
+ dsdt_buffer = ACPI_ALLOCATE(len);
+ if (!dsdt_buffer) {
+ printk("error when allocating %lu bytes of memory.\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("error trying to read %lu bytes from %s.\n", len, ramfs_dsdt_name);
+ ACPI_FREE(dsdt_buffer);
+ goto err;
+ }
+
+ printk("successfully read %lu bytes from %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)
@@ -319,13 +379,18 @@ acpi_os_table_override(struct acpi_table_header * existing_table,
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;
}