When a new variant is created, it needs to have a path to its SPD binary
defined. Currently, this is done by setting SPD_SOURCES to a placeholder
SPD file, which just contains zero bytes.
To remove the need for a placeholder file, automatically generate a
single-byte spd.bin in lib/Makefile.inc when SPD_SOURCES is set to the
marker value 'placeholder'.
BUG=b:191776301
TEST=Change cappy/memory/Makefile to `SPD_SOURCES = placeholder`. Build
and check that spd.bin contains a single zero byte.
Signed-off-by: Reka Norman <rekanorman@google.com>
Change-Id: I11f8f9b7ea3bc32aa5c7a617558572a5c1c74c72
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57795
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>