kern/log: serialize the start of the log and shell threads

2 files changed, 12 insertions, 2 deletions

diff --git a/kern/kernel.c b/kern/kernel.c
index 30dff08e..f41956e8 100644
--- a/kern/kernel.c
+++ b/kern/kernel.c
@@ -21,7 +21,6 @@
 #include <kern/llsync.h>
 #include <kern/log.h>
 #include <kern/percpu.h>
-#include <kern/shell.h>
 #include <kern/sleepq.h>
 #include <kern/sref.h>
 #include <kern/task.h>
@@ -52,7 +51,6 @@ kernel_main(void)
     llsync_setup();
     sref_setup();
     vm_page_info();
-    shell_start();
     log_start();
 
 #ifdef X15_RUN_TEST_MODULE
diff --git a/kern/log.c b/kern/log.c
index 6adc378b..a3b34f37 100644
--- a/kern/log.c
+++ b/kern/log.c
@@ -228,11 +228,13 @@ log_run(void *arg)
 {
     unsigned long flags, index, nr_overruns;
     struct log_record record;
+    bool start_shell;
     int error;
 
     (void)arg;
 
     nr_overruns = 0;
+    start_shell = true;
 
     spinlock_lock_intr_save(&log_lock, &flags);
 
@@ -240,6 +242,16 @@ log_run(void *arg)
 
     for (;;) {
         while (index == cbuf_end(&log_cbuf)) {
+            /*
+             * Starting the shell after the log thread sleeps for the first
+             * time cleanly serializes log messages and shell prompt, making
+             * a clean ordered output.
+             */
+            if (start_shell) {
+                shell_start();
+                start_shell = false;
+            }
+
             thread_sleep(&log_lock, &log_cbuf, "log_cbuf");
         }