grab the git hash and inject it into every log file header

src/modules/sdlog2/sdlog2_messages.h

@@ -250,8 +250,26 @@ struct log_GVSP_s {
 	float vz;
 };
 
+/* --- FWRV - FIRMWARE REVISION --- */
+#define LOG_FWRV_MSG 20
+struct log_FWRV_s {
+	char    fw_revision[64];
+};
+
 #pragma pack(pop)
 
+
+/*
+ GIT_VERSION is defined at build time via a Makefile call to the
+ git command line. We create a fake log message format for 
+ the firmware revision "FWRV" that is written to every log
+ header. This makes it easier to determine which version
+ of the firmware was running when a log was created.
+ */
+#define FREEZE_STR(s) #s
+#define STRINGIFY(s) FREEZE_STR(s)
+#define FW_VERSION_STR  STRINGIFY(GIT_VERSION)
+
 /* construct list of all message formats */
 
 static const struct log_format_s log_formats[] = {
@@ -274,6 +292,7 @@ static const struct log_format_s log_formats[] = {
 	LOG_FORMAT(GPSP, "BLLfffbBffff", "AltRel,Lat,Lon,Alt,Yaw,LoiterR,LoiterDir,NavCmd,P1,P2,P3,P4"),
 	LOG_FORMAT(ESC, "HBBBHHHHHHfH", "Counter,NumESC,Conn,N,Ver,Adr,Volt,Amp,RPM,Temp,SetP,SetPRAW"),
 	LOG_FORMAT(GVSP, "fff", "VX,VY,VZ"),
+	LOG_FORMAT(FWRV,"Z",FW_VERSION_STR),
 };
 
 static const int log_formats_num = sizeof(log_formats) / sizeof(struct log_format_s);