ACPI / tables: table override from built-in initrd

In some scenario, we need to build initrd with kernel in a single image.
This can simplify system deployment process by downloading the whole system
once, such as in IC verification.

This patch adds support to override ACPI tables from built-in initrd.

Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com>
[ rjw: Minor cleanups ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 48eabb6c2d4f..8fccbe49612a 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -473,14 +473,22 @@ static DECLARE_BITMAP(acpi_initrd_installed, NR_ACPI_INITRD_TABLES);
 
 void __init acpi_table_upgrade(void)
 {
-        void *data = (void *)initrd_start;
-        size_t size = initrd_end - initrd_start;
+        void *data;
+        size_t size;
         int sig, no, table_nr = 0, total_offset = 0;
         long offset = 0;
         struct acpi_table_header *table;
         char cpio_path[32] = "kernel/firmware/acpi/";
         struct cpio_data file;
 
+        if (IS_ENABLED(CONFIG_ACPI_TABLE_OVERRIDE_VIA_BUILTIN_INITRD)) {
+                data = __initramfs_start;
+                size = __initramfs_size;
+        } else {
+                data = (void *)initrd_start;
+                size = initrd_end - initrd_start;
+        }
+
         if (data == NULL || size == 0)
                 return;