[PATCH v3 2/6] um: Add os_info() for pre-boot information messages

From: Masami Hiramatsu
Date: Wed May 17 2017 - 13:20:43 EST


Add os_info() for printing out pre-boot information
level messages in stderr. The messages via os_info()
are suppressed by "quiet" kernel command line.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
arch/um/include/shared/os.h | 2 ++
arch/um/os-Linux/util.c | 25 +++++++++++++++++++++++++
2 files changed, 27 insertions(+)

diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index cd1fa97..9e95bce 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -242,6 +242,8 @@ extern void setup_hostinfo(char *buf, int len);
extern void os_dump_core(void) __attribute__ ((noreturn));
extern void um_early_printk(const char *s, unsigned int n);
extern void os_fix_helper_signals(void);
+extern void os_info(const char *fmt, ...)
+ __attribute__ ((format (printf, 1, 2)));

/* time.c */
extern void os_idle_sleep(unsigned long long nsecs);
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index faee55e..c9bad1b 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -13,6 +13,7 @@
#include <wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
+#include <init.h>
#include <os.h>

void stack_protections(unsigned long address)
@@ -152,3 +153,27 @@ void um_early_printk(const char *s, unsigned int n)
{
printf("%.*s", n, s);
}
+
+static int quiet_info;
+
+static int __init quiet_cmd_param(char *str, int *add)
+{
+ quiet_info = 1;
+ return 0;
+}
+
+__uml_setup("quiet", quiet_cmd_param,
+"quiet\n"
+" Turns off information messages during boot.\n\n");
+
+void os_info(const char *fmt, ...)
+{
+ va_list list;
+
+ if (quiet_info)
+ return;
+
+ va_start(list, fmt);
+ vfprintf(stderr, fmt, list);
+ va_end(list);
+}