[build] Replace random build ID with a deterministic one
Calculate the build ID as a checksum over the input files. Since the
input files include $(BIN)/version.%.o which itself includes the build
target name (from which TGT_LD_FLAGS is calculated), this should be
sufficient to meet the requirement that the build ID be unique for
each $(BIN)/%.tmp even within the same build run.
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
diff --git a/src/Makefile.housekeeping b/src/Makefile.housekeeping
index 81bd3c4..9b52e12 100644
--- a/src/Makefile.housekeeping
+++ b/src/Makefile.housekeeping
@@ -1163,7 +1163,13 @@
# Command to generate build ID. Must be unique for each $(BIN)/%.tmp,
# even within the same build run.
#
-BUILD_ID_CMD := perl -e 'printf "0x%08x", int ( rand ( 0xffffffff ) );'
+# The build ID is supposed to be collision-free across all ROMs that
+# might ever end up installed in the same system. It doesn't just
+# disambiguate targets within a single build; it also disambiguates
+# different builds (such as builds for multiple ROMs all built from
+# the same blib.a).
+#
+BUILD_ID_CMD = sha1sum $^ | sort | cksum | awk '{printf "0x%08x", $$1}'
# Build timestamp
#
