efi: Add 'systab' information to Documentation/ABI

It's not clear right now that the order in which entries are displayed
in /sys/firmware/efi/systab actually forms an ABI that userspace tools
rely upon.

Document the ABI along with the userspace tool that cares.

Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/Documentation/ABI/testing/sysfs-firmware-efi b/Documentation/ABI/testing/sysfs-firmware-efi
index 05874da7ce80302d92e15781deb90c2f1522c9e4..e794eac32a90a51c4d01577affe71466cde99a1f 100644 (file)
--- a/Documentation/ABI/testing/sysfs-firmware-efi
+++ b/Documentation/ABI/testing/sysfs-firmware-efi
@@ -18,3 +18,13 @@ Contact:     Dave Young <dyoung@redhat.com>
 Description:   It shows the physical address of config table entry in the EFI
                system table.
 Users:         Kexec
+
+What:          /sys/firmware/efi/systab
+Date:          April 2005
+Contact:       linux-efi@vger.kernel.org
+Description:   Displays the physical addresses of all EFI Configuration
+               Tables found via the EFI System Table. The order in
+               which the tables are printed forms an ABI and newer
+               versions are always printed first, i.e. ACPI20 comes
+               before ACPI.
+Users:         dmidecode