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-rw-r--r--Documentation/kernel-parameters.txt4
-rw-r--r--init/do_mounts.c24
2 files changed, 26 insertions, 2 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a0362d5a911e..a571495a9ac6 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1504,6 +1504,10 @@ and is between 256 and 4096 characters. It is defined in the file
rootfstype= [KNL] Set root filesystem type
+ rootwait [KNL] Wait (indefinitely) for root device to show up.
+ Useful for devices that are detected asynchronously
+ (e.g. USB and MMC devices).
+
rw [KNL] Mount root device read-write on boot
S [KNL] Run init in single mode
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 46fe407fb03e..4efa1e5385e3 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -25,6 +25,7 @@ int __initdata rd_doload; /* 1 = load RAM disk, 0 = don't load */
int root_mountflags = MS_RDONLY | MS_SILENT;
char * __initdata root_device_name;
static char __initdata saved_root_name[64];
+static int __initdata root_wait;
dev_t ROOT_DEV;
@@ -216,6 +217,16 @@ static int __init root_dev_setup(char *line)
__setup("root=", root_dev_setup);
+static int __init rootwait_setup(char *str)
+{
+ if (*str)
+ return 0;
+ root_wait = 1;
+ return 1;
+}
+
+__setup("rootwait", rootwait_setup);
+
static char * __initdata root_mount_data;
static int __init root_data_setup(char *str)
{
@@ -438,11 +449,20 @@ void __init prepare_namespace(void)
root_device_name += 5;
}
- is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
-
if (initrd_load())
goto out;
+ /* wait for any asynchronous scanning to complete */
+ if ((ROOT_DEV == 0) && root_wait) {
+ printk(KERN_INFO "Waiting for root device %s...\n",
+ saved_root_name);
+ while (driver_probe_done() != 0 ||
+ (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
+ msleep(100);
+ }
+
+ is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
+
if (is_floppy && rd_doload && rd_load_disk(0))
ROOT_DEV = Root_RAM0;