From bd351002c07a35e3f5f54370024ab7cdc6b6ee67 Mon Sep 17 00:00:00 2001
From: hev <r@hev.cc>
Date: Sat, 20 Apr 2024 23:53:48 +0800
Subject: [PATCH] Build: Read rev-id from file.

---
 build.mk | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/build.mk b/build.mk
index 421ca6995..244f484c5 100644
--- a/build.mk
+++ b/build.mk
@@ -5,4 +5,16 @@ rwildcard=$(foreach d,$(wildcard $1*), \
           $(filter $(subst *,%,$2),$d))
 
 SRCFILES=$(call rwildcard,$(SRCDIR)/,*.c *.S)
-VERSION_CFLAGS=-DCOMMIT_ID=\"$(shell git -C $(SRCDIR) rev-parse --short HEAD)\"
+
+ifeq ($(REV_ID),)
+  ifneq (,$(wildcard .rev-id))
+    REV_ID=$(shell cat .rev-id)
+  endif
+  ifeq ($(REV_ID),)
+    REV_ID=$(shell git -C $(SRCDIR) rev-parse --short HEAD)
+  endif
+  ifeq ($(REV_ID),)
+    REV_ID=unknown
+  endif
+endif
+VERSION_CFLAGS=-DCOMMIT_ID=\"$(REV_ID)\"