From fbaf7dfdc1fba38c981946932b76fde81b403929 Mon Sep 17 00:00:00 2001
From: Yong Cong Sin <ycsin@meta.com>
Date: Tue, 2 Apr 2024 14:48:02 +0800
Subject: [PATCH] kernel: banner: use BUILD_VERSION only if not empty

The `BUILD_VERSION` can be defined but empty when built
without git, causing version to be missing from the banner:

```
*** Booting Zephyr OS build  ***
Hello World! qemu_riscv64
```

Let's check if it is empty before using it, so that
`KERNEL_VERSION_STRING`, which is generated independently
with cmake can be used as a fallback:

```
*** Booting Zephyr OS build 3.5.0 ***
Hello World! qemu_riscv64
```

Signed-off-by: Yong Cong Sin <ycsin@meta.com>
---
 kernel/banner.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/banner.c b/kernel/banner.c
index 5274c3e0d6..dc2506fb9b 100644
--- a/kernel/banner.c
+++ b/kernel/banner.c
@@ -17,7 +17,7 @@
 #endif /* defined(CONFIG_BOOT_DELAY) && (CONFIG_BOOT_DELAY > 0) */
 
 #ifndef BANNER_VERSION
-#ifdef BUILD_VERSION
+#if defined(BUILD_VERSION) && !IS_EMPTY(BUILD_VERSION)
 #define BANNER_VERSION STRINGIFY(BUILD_VERSION)
 #else
 #define BANNER_VERSION KERNEL_VERSION_STRING