[3c595] Fix compilation when "char" is unsigned by default

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/drivers/net/3c595.c b/src/drivers/net/3c595.c
index 2338c54b79aadeb3e03c34a09e01095f53cd376a..92d38cfc5b6c7990edcc0c890de329bec4c49412 100644 (file)
--- a/src/drivers/net/3c595.c
+++ b/src/drivers/net/3c595.c
@@ -391,7 +391,7 @@ vxsetlink(void)
 {       
     int i, j;
     char *reason, *warning;
-    static char prev_conn = -1;
+    static signed char prev_conn = -1;
 
     if (prev_conn == -1) {
         prev_conn = vx_connector;