Possible to delay boot process to boot from USB subsystem?

Possible to delay boot process to boot from USB subsystem?

[Bill Catlan]

Hello,

The below message appeared on linux-kernel in June 2002.  The patch allows
booting from a USB harddrive and was designed for the 2.4.14-pre8-ext3 kernel,
but I was able to manually apply it to a Debian 2.4.18 kernel.

I am now trying to upgrade to a 2.4.26 kernel, and I am unable to create the
same "boot from floppy with rootfs on a USB drive" scenario that I created with
the modified 2.4.18 kernel.  I believe my current issue with the 2.4.26 kernel
is the same race condition as on the 2.4.18 kernel since I get the "Initializing
USB Mass Storage driver..." notice, but then i get "Kernel panic: No init found.
Try passing init= option to kernel."  Given time, I suspect that the USB storage
subsystem would come online and the kernel would be able to mount the rootfs on
it.

fs/super.c has change dramatically and the below patch now seems obsolete.

Is there a similar patch for newer kernels - or any other way to cause the boot
process to pause between loading the kernel and modules and running /sbin/init?

TIA.

Bill

On Sun, Jun 02, 2002 at 10:13:22PM +0200, Paul Stoeber wrote:
> It simply sleeps 10 seconds before mount_block_root().
>
> I get an 'Unable to mount root' panic if I don't apply it,
> because the attached device rolls in too late.

A while ago I made the patch below. I retries every second until the root
device appears. Advantages:
- no delay when the device is already there
- it also works if it takes longer than 10s to find the harddisk
  (for example, if you plug it in later)

I don't know if it applies cleanly to current kernels.

Eric

--- linux-2.4.14-pre8-ext3/fs/super.c.orig	Fri Nov 16 00:59:18 2001
+++ linux-2.4.14-pre8-ext3/fs/super.c	Fri Nov 16 01:07:26 2001
@@ -1009,11 +1009,13 @@
 		 * Allow the user to distinguish between failed open
 		 * and bad superblock on root device.
 		 */
-		printk ("VFS: Cannot open root device \"%s\" or %s\n",
+		printk ("VFS: Cannot open root device \"%s\" or %s, retrying in 1s.\n",
 			root_device_name, kdevname (ROOT_DEV));
-		printk ("Please append a correct \"root=\" boot option\n");
-		panic("VFS: Unable to mount root fs on %s",
-			kdevname(ROOT_DEV));
+
+		/* wait 1 second and try again */
+		current->state = TASK_INTERRUPTIBLE;
+		schedule_timeout(HZ);
+		goto retry;
 	}

 	check_disk_change(ROOT_DEV);
-

Re: Possible to delay boot process to boot from USB subsystem?

[Randy.Dunlap]

On Sun, 2 May 2004 19:27:08 -0400 "Bill Catlan" <wcatlan@yahoo.com> wrote:

| Hello,
| 
| The below message appeared on linux-kernel in June 2002.  The patch allows
| booting from a USB harddrive and was designed for the 2.4.14-pre8-ext3 kernel,
| but I was able to manually apply it to a Debian 2.4.18 kernel.
| 
| I am now trying to upgrade to a 2.4.26 kernel, and I am unable to create the
| same "boot from floppy with rootfs on a USB drive" scenario that I created with
| the modified 2.4.18 kernel.  I believe my current issue with the 2.4.26 kernel
| is the same race condition as on the 2.4.18 kernel since I get the "Initializing
| USB Mass Storage driver..." notice, but then i get "Kernel panic: No init found.
| Try passing init= option to kernel."  Given time, I suspect that the USB storage
| subsystem would come online and the kernel would be able to mount the rootfs on
| it.
| 
| fs/super.c has change dramatically and the below patch now seems obsolete.
| 
| Is there a similar patch for newer kernels - or any other way to cause the boot
| process to pause between loading the kernel and modules and running /sbin/init?
| 
| TIA.
| 
| Bill
| 
| On Sun, Jun 02, 2002 at 10:13:22PM +0200, Paul Stoeber wrote:
| > It simply sleeps 10 seconds before mount_block_root().
| >
| > I get an 'Unable to mount root' panic if I don't apply it,
| > because the attached device rolls in too late.
| 
| A while ago I made the patch below. I retries every second until the root
| device appears. Advantages:
| - no delay when the device is already there
| - it also works if it takes longer than 10s to find the harddisk
|   (for example, if you plug it in later)
| 
| I don't know if it applies cleanly to current kernels.
| 
| Eric
| 
| --- linux-2.4.14-pre8-ext3/fs/super.c.orig	Fri Nov 16 00:59:18 2001
| +++ linux-2.4.14-pre8-ext3/fs/super.c	Fri Nov 16 01:07:26 2001
| @@ -1009,11 +1009,13 @@
|  		 * Allow the user to distinguish between failed open
|  		 * and bad superblock on root device.
|  		 */
| -		printk ("VFS: Cannot open root device \"%s\" or %s\n",
| +		printk ("VFS: Cannot open root device \"%s\" or %s, retrying in 1s.\n",
|  			root_device_name, kdevname (ROOT_DEV));
| -		printk ("Please append a correct \"root=\" boot option\n");
| -		panic("VFS: Unable to mount root fs on %s",
| -			kdevname(ROOT_DEV));
| +
| +		/* wait 1 second and try again */
| +		current->state = TASK_INTERRUPTIBLE;
| +		schedule_timeout(HZ);
| +		goto retry;
|  	}
| 
|  	check_disk_change(ROOT_DEV);
| -

I updated that patch to 2.4.22 but haven't checked it since then.
I can't test it... if you can, that would be great.
If it doesn't apply cleanly to 2.4.26, let me know and I'll work
on it.

Patch is here:
  http://www.xenotime.net/linux/usb/usbboot-2422.patch

--
~Randy

Re: Possible to delay boot process to boot from USB subsystem?

[Bill Catlan]

Thanks Randy.  As the below output shows, your patch
applies cleanly to 2.4.26 source, but I have not yet
had the chance to compile and test my configuration.

[root@plain linux-2.4.26]# patch init/do_mounts.c
usbboot-2422.patch 
patching file init/do_mounts.c
Hunk #1 succeeded at 367 (offset 1 line).

Bill
 

--- "Randy.Dunlap" <rddunlap@osdl.org> wrote:
> I updated that patch to 2.4.22 but haven't checked
> it since then.
> I can't test it... if you can, that would be great.
> If it doesn't apply cleanly to 2.4.26, let me know
> and I'll work
> on it.
> 
> Patch is here:
>  
> http://www.xenotime.net/linux/usb/usbboot-2422.patch
> 
> --
> ~Randy



	
		
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Re: Possible to delay boot process to boot from USB subsystem?

[Willy Tarreau]

Hi,

I include the following patch in all my kernels. It adds a "setuptime" boot
option which allows one to specify how many milliseconds to wait before
mounting the root FS. I usually wait 2500 ms to boot on USB flash, but I
once saw a machine which required a bit more (4 sec). The advantage is that
if it isn't enough, just reboot and change the paramter.

Regards,
Willy


diff -urN linux-2.4.23-rc3/init/main.c linux-2.4.23-rc3-setuptime/init/main.c
--- linux-2.4.23-rc3/init/main.c	Fri Oct 10 08:47:16 2003
+++ linux-2.4.23-rc3-setuptime/init/main.c	Sun Nov 23 18:12:19 2003
@@ -127,6 +127,7 @@
 
 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
+static int setuptime;	/* time(ms) to let devices set up before root mount */
 
 static int __init profile_setup(char *str)
 {
@@ -137,6 +138,15 @@
 
 __setup("profile=", profile_setup);
 
+static int __init setuptime_setup(char *str)
+{
+    int par;
+    if (get_option(&str,&par)) setuptime = par;
+	return 1;
+}
+
+__setup("setuptime=", setuptime_setup);
+
 static int __init checksetup(char *line)
 {
 	struct kernel_param *p;
@@ -553,12 +563,26 @@
 
 extern void prepare_namespace(void);
 
+static int finish_setup()
+{
+	int tleft;
+	if (setuptime) {
+		printk("Waiting %d ms for devices to set up.\n", setuptime);
+		tleft = setuptime * HZ / 1000;
+		while (tleft) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			tleft = schedule_timeout(tleft);
+		}
+	}
+}
+
 static int init(void * unused)
 {
 	struct files_struct *files;
 	lock_kernel();
 	do_basic_setup();
 
+	finish_setup();
 	prepare_namespace();
 
 	/*

Re: Possible to delay boot process to boot from USB subsystem?

[Bill Catlan]

Randy,

Thanks for the patch, but it does not work for 2.4.26.  The kernel panic I get
("Kernel panic: No init found. Try passing init= option to kernel.")  is
generated by the init() function in init/main.c.  Willy's patch applies to
init/main.c, perhaps yours should now as well (i.e., in later kernels)?  (I have
not tested Willy's patch, but he claims success with a 2.4.23 kernel.)

I like your approach better because I do not have to set a time, it just keeps
trying in a loop.  Since mounting the rootfs is a critical step, I don't mind
the infinite looping until success - especially with hot swappable devices.  I
had nice functionality on a 2.4.18 kernel, but would rather keep current with
the kernel.

Hope this helps.  Please let me know what you think might be possible, as well
as a timeframe, if at all possible.  Thanks.

Bill

----- Original Message ----- 
From: "Randy.Dunlap" <rddunlap@osdl.org>
To: "Bill Catlan" <wcatlan@yahoo.com>
Cc: <linux-kernel@vger.kernel.org>
Sent: Sunday, May 02, 2004 9:27 PM
Subject: Re: Possible to delay boot process to boot from USB subsystem?


> On Sun, 2 May 2004 19:27:08 -0400 "Bill Catlan" <wcatlan@yahoo.com> wrote:
>
> | Hello,
> |
> | The below message appeared on linux-kernel in June 2002.  The patch allows
> | booting from a USB harddrive and was designed for the 2.4.14-pre8-ext3
kernel,
> | but I was able to manually apply it to a Debian 2.4.18 kernel.
> |
> | I am now trying to upgrade to a 2.4.26 kernel, and I am unable to create the
> | same "boot from floppy with rootfs on a USB drive" scenario that I created
with
> | the modified 2.4.18 kernel.  I believe my current issue with the 2.4.26
kernel
> | is the same race condition as on the 2.4.18 kernel since I get the
"Initializing
> | USB Mass Storage driver..." notice, but then i get "Kernel panic: No init
found.
> | Try passing init= option to kernel."  Given time, I suspect that the USB
storage
> | subsystem would come online and the kernel would be able to mount the rootfs
on
> | it.
> |
> | fs/super.c has change dramatically and the below patch now seems obsolete.
> |
> | Is there a similar patch for newer kernels - or any other way to cause the
boot
> | process to pause between loading the kernel and modules and running
/sbin/init?
> |
> | TIA.
> |
> | Bill
> |
> | On Sun, Jun 02, 2002 at 10:13:22PM +0200, Paul Stoeber wrote:
> | > It simply sleeps 10 seconds before mount_block_root().
> | >
> | > I get an 'Unable to mount root' panic if I don't apply it,
> | > because the attached device rolls in too late.
> |
> | A while ago I made the patch below. I retries every second until the root
> | device appears. Advantages:
> | - no delay when the device is already there
> | - it also works if it takes longer than 10s to find the harddisk
> |   (for example, if you plug it in later)
> |
> | I don't know if it applies cleanly to current kernels.
> |
> | Eric
> |
> | --- linux-2.4.14-pre8-ext3/fs/super.c.orig Fri Nov 16 00:59:18 2001
> | +++ linux-2.4.14-pre8-ext3/fs/super.c Fri Nov 16 01:07:26 2001
> | @@ -1009,11 +1009,13 @@
> |  * Allow the user to distinguish between failed open
> |  * and bad superblock on root device.
> |  */
> | - printk ("VFS: Cannot open root device \"%s\" or %s\n",
> | + printk ("VFS: Cannot open root device \"%s\" or %s, retrying in 1s.\n",
> |  root_device_name, kdevname (ROOT_DEV));
> | - printk ("Please append a correct \"root=\" boot option\n");
> | - panic("VFS: Unable to mount root fs on %s",
> | - kdevname(ROOT_DEV));
> | +
> | + /* wait 1 second and try again */
> | + current->state = TASK_INTERRUPTIBLE;
> | + schedule_timeout(HZ);
> | + goto retry;
> |  }
> |
> |  check_disk_change(ROOT_DEV);
> | -
>
> I updated that patch to 2.4.22 but haven't checked it since then.
> I can't test it... if you can, that would be great.
> If it doesn't apply cleanly to 2.4.26, let me know and I'll work
> on it.
>
> Patch is here:
>   http://www.xenotime.net/linux/usb/usbboot-2422.patch
>
> --
> ~Randy

Re: Possible to delay boot process to boot from USB subsystem?

[Bill Catlan]

Thanks Willy.  I like to automatic looping of Randy's patch (I had it working
nicely on a 2.4.18 kernel) because I don't have to set a time in case one
machine takes longer than another.

So far, however, I haven't got Randy's patch working for a newer kernel, so I
may try yours.

Would I only have to run make in the directory where I'm patching the file, then
make bzImage, make modules_install, and make install from the top level to apply
your patch?  Compiling all of my modules takes a long time, with random lock-ups
during compile gumming up the works as well. :-/  Any tips appreciated.

Thanks.

Bill

----- Original Message ----- 
From: "Willy Tarreau" <willy@w.ods.org>
To: "Bill Catlan" <wcatlan@yahoo.com>
Cc: <linux-kernel@vger.kernel.org>
Sent: Monday, May 03, 2004 1:34 AM
Subject: Re: Possible to delay boot process to boot from USB subsystem?


> Hi,
>
> I include the following patch in all my kernels. It adds a "setuptime" boot
> option which allows one to specify how many milliseconds to wait before
> mounting the root FS. I usually wait 2500 ms to boot on USB flash, but I
> once saw a machine which required a bit more (4 sec). The advantage is that
> if it isn't enough, just reboot and change the paramter.
>
> Regards,
> Willy
>
>
> diff -urN linux-2.4.23-rc3/init/main.c linux-2.4.23-rc3-setuptime/init/main.c
> --- linux-2.4.23-rc3/init/main.c Fri Oct 10 08:47:16 2003
> +++ linux-2.4.23-rc3-setuptime/init/main.c Sun Nov 23 18:12:19 2003
> @@ -127,6 +127,7 @@
>
>  static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
>  char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
> +static int setuptime; /* time(ms) to let devices set up before root mount */
>
>  static int __init profile_setup(char *str)
>  {
> @@ -137,6 +138,15 @@
>
>  __setup("profile=", profile_setup);
>
> +static int __init setuptime_setup(char *str)
> +{
> +    int par;
> +    if (get_option(&str,&par)) setuptime = par;
> + return 1;
> +}
> +
> +__setup("setuptime=", setuptime_setup);
> +
>  static int __init checksetup(char *line)
>  {
>   struct kernel_param *p;
> @@ -553,12 +563,26 @@
>
>  extern void prepare_namespace(void);
>
> +static int finish_setup()
> +{
> + int tleft;
> + if (setuptime) {
> + printk("Waiting %d ms for devices to set up.\n", setuptime);
> + tleft = setuptime * HZ / 1000;
> + while (tleft) {
> + set_current_state(TASK_INTERRUPTIBLE);
> + tleft = schedule_timeout(tleft);
> + }
> + }
> +}
> +
>  static int init(void * unused)
>  {
>   struct files_struct *files;
>   lock_kernel();
>   do_basic_setup();
>
> + finish_setup();
>   prepare_namespace();
>
>   /*
>

Re: Possible to delay boot process to boot from USB subsystem?

[Willy TARREAU]

On Mon, May 03, 2004 at 04:44:30PM -0400, Bill Catlan wrote:
> Thanks Willy.  I like to automatic looping of Randy's patch (I had it working
> nicely on a 2.4.18 kernel) because I don't have to set a time in case one
> machine takes longer than another.

I certainly can understand this, although I've never tried it yet.

> So far, however, I haven't got Randy's patch working for a newer kernel, so I
> may try yours.
> 
> Would I only have to run make in the directory where I'm patching the file, then
> make bzImage, make modules_install, and make install from the top level to apply
> your patch?  Compiling all of my modules takes a long time, with random lock-ups
> during compile gumming up the works as well. :-/  Any tips appreciated.

No exactly, you should not run 'make' from the 'init' directory, but rather
tell 'make' where you want it to check for changes :

# make bzImage SUBDIRS=init

It will skip over other directories (such as drivers, fs, net, ...) and
only recompile below 'init'. I do this very often and it's very convenient.
However, you should not do this if you have changed certain compile options
or things that might imply different dependencies.

A hint to check if it has been correctly configured :

# nm vmlinux | grep setuptime
c01b2b80 d __setup_setuptime_setup
c01ab039 d __setup_str_setuptime_setup
c015700c b setuptime
c01b31b0 t setuptime_setup

Regards,
Willy

Re: Possible to delay boot process to boot from USB subsystem?

[Randy.Dunlap]

Bill,

(replying to:  http://lkml.org/lkml/2004/5/3/124,
I don't have mailbox access to your email ATM)


I wish that I had a way to test this patch.
Apparently Willy does, so I recommend his patch.... :)
with one change:

change
+static int setuptime;	/* time(ms) to let devices set up before root mount */

to
+static int setuptime = 10000;	/* time(ms) to let devices set up before root mount */


or 60000 (= 1 minute).  Whatever is comfortable for you.

Willy, it seems that some default value would be good there.

Later,
--
~Randy

Re: Possible to delay boot process to boot from USB subsystem?

[Willy Tarreau]

Hi Randy,

On Mon, May 03, 2004 at 07:32:05PM -0700, Randy.Dunlap wrote:
> I wish that I had a way to test this patch.
> Apparently Willy does, so I recommend his patch.... :)

You should never recommend anything from me to anyone if you want to
keep some friends :-)

> with one change:
> 
> change
> +static int setuptime;	/* time(ms) to let devices set up before root mount */
> 
> to
> +static int setuptime = 10000;	/* time(ms) to let devices set up before root mount */
> 
> 
> or 60000 (= 1 minute).  Whatever is comfortable for you.
> 
> Willy, it seems that some default value would be good there.

It was intentionnal, I don't like to change the default kernel behaviour.
So by default it's 0 and behaves as if the patch was not applied. However,
I think that a very small value (a few seconds) may be acceptable by default.
Of course, if Bill doesn't use the patch anywhere else, he should be fine
with a higher value.

Another (dirty) hack would be to export this variable, keep it to 0 by
default, and have usb_hub_thread() set it to a reasonable value when
starting khubd.

Regards,
Willy

Re: Possible to delay boot process to boot from USB subsystem?

[Paulo Marques]

Bill Catlan wrote:

> Randy,
> 
> Thanks for the patch, but it does not work for 2.4.26.  The kernel panic I get
> ("Kernel panic: No init found. Try passing init= option to kernel.")  is
> generated by the init() function in init/main.c.  Willy's patch applies to
> init/main.c, perhaps yours should now as well (i.e., in later kernels)?  (I have
> not tested Willy's patch, but he claims success with a 2.4.23 kernel.)


This is a completely different error from "VFS: Cannot open root device" or 
"unable to mount root".

Are you sure you have a "/sbin" directory with an *executable* "init" file on 
the usb harddrive?

Does your init file depend on libraries that you do not have under "/lib"? (you 
can check with "ldd init")

If your init is a script, does it specify a complete path to the interpreter, 
and do you have an *executable* interpreter there? Does the interpreter require 
libraries or is it static?

I hope this helps,

-- 
Paulo Marques - www.grupopie.com
"In a world without walls and fences who needs windows and gates?"

Re: Possible to delay boot process to boot from USB subsystem?

[Bill Catlan]

Hi Paulo,

Thanks for the feedback.  I was starting to think the same thing myself, but it
turns out the root cause is the same thing - namely, slow startup of the USB
storage subsystem.

The differing symptom (i.e., different error messages) is entirely due to the
difference in kernel versions.  I got my setup (2.4.26) working with Willy's
patch.  I am going to re-test Randy's patch as I needed to modify the "preload"
order of my modules in my initrd image in order to even get Willy's patch to
work.  With the reordering, I suspect (50/50 chance I think) that Randy's patch
for the 2.4.22 kernel may work on the 2.4.26 kernel as well.

I originally thought that I had compiled the necessary scsi and usb stuff into
the kernel, but upon eventually revisiting my kernel config file I learned along
the way and to my chagrin that I had left them as modules, adding this slight
complication.

Stay tuned for our next episode! :)

Bill

----- Original Message ----- 
From: "Paulo Marques" <pmarques@grupopie.com>
To: "Bill Catlan" <wcatlan@yahoo.com>
Cc: "Randy.Dunlap" <rddunlap@osdl.org>; <linux-kernel@vger.kernel.org>
Sent: Tuesday, May 04, 2004 2:53 PM
Subject: Re: Possible to delay boot process to boot from USB subsystem?


> Bill Catlan wrote:
>
> > Randy,
> >
> > Thanks for the patch, but it does not work for 2.4.26.  The kernel panic I
get
> > ("Kernel panic: No init found. Try passing init= option to kernel.")  is
> > generated by the init() function in init/main.c.  Willy's patch applies to
> > init/main.c, perhaps yours should now as well (i.e., in later kernels)?  (I
have
> > not tested Willy's patch, but he claims success with a 2.4.23 kernel.)
>
>
> This is a completely different error from "VFS: Cannot open root device" or
> "unable to mount root".
>
> Are you sure you have a "/sbin" directory with an *executable* "init" file on
> the usb harddrive?
>
> Does your init file depend on libraries that you do not have under "/lib"?
(you
> can check with "ldd init")
>
> If your init is a script, does it specify a complete path to the interpreter,
> and do you have an *executable* interpreter there? Does the interpreter
require
> libraries or is it static?
>
> I hope this helps,
>
> -- 
> Paulo Marques - www.grupopie.com
> "In a world without walls and fences who needs windows and gates?"