x86: acpi: Support external GNVS tables
At present U-Boot puts a magic number in the ASL for the GNVS table and
searches for it later.
Add a Kconfig option to use a different approach, where the ASL files
declare the table as an external symbol. U-Boot can then put it wherever
it likes, without any magic numbers or searching.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/acpi/global_nvs.h b/arch/x86/include/asm/acpi/global_nvs.h
index d56d35c..a552cf6 100644
--- a/arch/x86/include/asm/acpi/global_nvs.h
+++ b/arch/x86/include/asm/acpi/global_nvs.h
@@ -11,6 +11,9 @@
* ACPI_GNVS_SIZE. They are to be used in platform's global_nvs.asl file
* to declare the GNVS OperationRegion, as well as write_acpi_tables()
* for the GNVS address runtime fix up.
+ *
+ * If using CONFIG_ACPI_GNVS_EXTERNAL, we don't need to locate the GNVS in
+ * DSDT, since it is created by code, so ACPI_GNVS_ADDR is unused.
*/
#define ACPI_GNVS_ADDR 0xdeadbeef
#define ACPI_GNVS_SIZE 0x100