--- a/fluid-mnf/serial.c	Fri Mar 13 05:40:23 2020 +0000
+++ b/fluid-mnf/serial.c	Fri Mar 13 05:53:20 2020 +0000
@@ -29,11 +29,14 @@
 #include <sys/ioctl.h>
 #include <asm/ioctls.h>
 #include <asm/termbits.h>
+#include <sys/errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
+extern int errno;
+
 
 /******************************************************************************
  * Linux Driver
@@ -208,7 +211,29 @@
 
 int serial_recv(char *buf, int size, int timeout)
 {
-	/* to be filled */
+	fd_set fds;
+	struct timeval tv;
+	int cc;
+
+	for (;;) {
+		FD_ZERO(&fds);
+		FD_SET(target_fd, &fds);
+		tv.tv_sec = timeout / 1000;
+		tv.tv_usec = (timeout % 1000) * 1000;
+		cc = select(target_fd+1, &fds, NULL, NULL, &tv);
+		if (cc < 0) {
+			if (errno == EINTR)
+				continue;
+			return E_OS + E_UART_DRV_RECV;
+		}
+		break;
+	}
+	if (cc == 0)
+		return cc;
+	cc = read(target_fd, buf, size);
+	if (cc <= 0)
+		cc = E_OS + E_UART_DRV_RECV;
+	return cc;
 }