3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

[Pavel Machek]

Hi!

> > > mmc0: new SDHC card at address b368                                             
> > > mmcblk0: mmc0:b368 USD   7.45 GiB                                               
> > >  mmcblk0: p1 p2 p3 p4                                                           
> > > VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
> > > -6        
> > > Please append a correct "root=" boot option; here are the available
> > > partitions: 
> > > b300         7822336 mmcblk0  driver: mmcblk                                    
> > >   b301          102400 mmcblk0p1 00082434-01                                    
> > >   b302         1048576 mmcblk0p2 00082434-02                                    
> > >   b303            1024 mmcblk0p3 00082434-03                                    
> > >   b304         6086656 mmcblk0p4 00082434-04                                    
> > > Kernel panic - not syncing: VFS: Unable to mount root fs on
> > > unknown-block(0,0)  
> > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-11208-gef74117-dirty
> > > #2        
> > 
> > Hmm...today's tip-top(899552d6) and ba36899 booted just fine for me. I
> > noticed something, you must have commits on top of your ba36899? Mine
> > shows 3.16.0-11149-gba36899.
> 
> Ok, thanks for info. I went back to 3.16, and it worked in same
> config, and went to 3.17, and it broke.

The problem is still there in 3.17-rc2. 3.16 does not have the
problem. Messages are still similar:

mmc0: new high speed SDHC card at address b368
mmcblk0: mmc0:b368 USD   7.45 GiB 
 mmcblk0: p1 p2 p3 p4
VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
-6
Please append a correct "root=" boot option; here are the available
partitions:
b300         7822336 mmcblk0  driver: mmcblk
  b301          102400 mmcblk0p1 00082434-01
  b302         1048576 mmcblk0p2 00082434-02
  b303            1024 mmcblk0p3 00082434-03
  b304         6086656 mmcblk0p4 00082434-04
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
CPU: 0 PID: 1 Comm: swapper/0 Not tainted
3.17.0-rc2-00368-gec0400b-dirty #83


What is going on there? Clearly partition table was parsed and
partitions are available; does the mention of unknown-block(0,0) mean
that kernel failed to parse the command line?

I replaced "root=/dev/mmcblk0p2" with "root=b302" and have a booting
system.

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: 3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

[Dinh Nguyen]

On Tue, Aug 26, 2014 at 6:47 AM, Pavel Machek <pavel@denx.de> wrote:
> Hi!
>
>> > > mmc0: new SDHC card at address b368
>> > > mmcblk0: mmc0:b368 USD   7.45 GiB
>> > >  mmcblk0: p1 p2 p3 p4
>> > > VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
>> > > -6
>> > > Please append a correct "root=" boot option; here are the available
>> > > partitions:
>> > > b300         7822336 mmcblk0  driver: mmcblk
>> > >   b301          102400 mmcblk0p1 00082434-01
>> > >   b302         1048576 mmcblk0p2 00082434-02
>> > >   b303            1024 mmcblk0p3 00082434-03
>> > >   b304         6086656 mmcblk0p4 00082434-04
>> > > Kernel panic - not syncing: VFS: Unable to mount root fs on
>> > > unknown-block(0,0)
>> > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-11208-gef74117-dirty
>> > > #2
>> >
>> > Hmm...today's tip-top(899552d6) and ba36899 booted just fine for me. I
>> > noticed something, you must have commits on top of your ba36899? Mine
>> > shows 3.16.0-11149-gba36899.
>>
>> Ok, thanks for info. I went back to 3.16, and it worked in same
>> config, and went to 3.17, and it broke.
>
> The problem is still there in 3.17-rc2. 3.16 does not have the
> problem. Messages are still similar:
>
> mmc0: new high speed SDHC card at address b368
> mmcblk0: mmc0:b368 USD   7.45 GiB
>  mmcblk0: p1 p2 p3 p4
> VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
> -6
> Please append a correct "root=" boot option; here are the available
> partitions:
> b300         7822336 mmcblk0  driver: mmcblk
>   b301          102400 mmcblk0p1 00082434-01
>   b302         1048576 mmcblk0p2 00082434-02
>   b303            1024 mmcblk0p3 00082434-03
>   b304         6086656 mmcblk0p4 00082434-04
> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted
> 3.17.0-rc2-00368-gec0400b-dirty #83
>
>
> What is going on there? Clearly partition table was parsed and
> partitions are available; does the mention of unknown-block(0,0) mean
> that kernel failed to parse the command line?
>
> I replaced "root=/dev/mmcblk0p2" with "root=b302" and have a booting
> system.


Can you do a bisect? 3.17-rc2 booted fine for me today:

EXT3-fs (mmcblk0p2): mounted filesystem with ordered data mode
VFS: Mounted root (ext3 filesystem) on device 179:2.
Freeing unused kernel memory: 252K (c052d000 - c056c000)
random: nonblocking pool is initialized

Poky 8.0 (Yocto Project 1.3 Reference Distro) 1.3 socfpga_cyclone5 ttyS0

socfpga_cyclone5 login: root
root@socfpga_cyclone5:~# uname -a
Linux socfpga_cyclone5 3.17.0-rc2-00006-gdd7ad78 #1 SMP Tue Aug 26
15:51:56 CDT 2014 armv7l GNU/Linux

Dinh

Re: 3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

[Pavel Machek]

Hi!

> > The problem is still there in 3.17-rc2. 3.16 does not have the
> > problem. Messages are still similar:
> >
> > mmc0: new high speed SDHC card at address b368
> > mmcblk0: mmc0:b368 USD   7.45 GiB
> >  mmcblk0: p1 p2 p3 p4
> > VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
> > -6
> > Please append a correct "root=" boot option; here are the available
> > partitions:
> > b300         7822336 mmcblk0  driver: mmcblk
> >   b301          102400 mmcblk0p1 00082434-01
> >   b302         1048576 mmcblk0p2 00082434-02
> >   b303            1024 mmcblk0p3 00082434-03
> >   b304         6086656 mmcblk0p4 00082434-04
> > Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted
> > 3.17.0-rc2-00368-gec0400b-dirty #83
> >
> >
> > What is going on there? Clearly partition table was parsed and
> > partitions are available; does the mention of unknown-block(0,0) mean
> > that kernel failed to parse the command line?
> >
> > I replaced "root=/dev/mmcblk0p2" with "root=b302" and have a booting
> > system.
> 
> 
> Can you do a bisect? 3.17-rc2 booted fine for me today:
> 
> EXT3-fs (mmcblk0p2): mounted filesystem with ordered data mode
> VFS: Mounted root (ext3 filesystem) on device 179:2.
> Freeing unused kernel memory: 252K (c052d000 - c056c000)
> random: nonblocking pool is initialized

Bisect would be hard... and I believe the problem is somewhere in
block layer now -- not socfpga-specific.

Best regards,
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: 3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

[Russell King - ARM Linux]

On Tue, Sep 09, 2014 at 01:49:41PM +0200, Pavel Machek wrote:
> Hi!
> 
> > > The problem is still there in 3.17-rc2. 3.16 does not have the
> > > problem. Messages are still similar:
> > >
> > > mmc0: new high speed SDHC card at address b368
> > > mmcblk0: mmc0:b368 USD   7.45 GiB
> > >  mmcblk0: p1 p2 p3 p4
> > > VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
> > > -6
> > > Please append a correct "root=" boot option; here are the available
> > > partitions:
> > > b300         7822336 mmcblk0  driver: mmcblk
> > >   b301          102400 mmcblk0p1 00082434-01
> > >   b302         1048576 mmcblk0p2 00082434-02
> > >   b303            1024 mmcblk0p3 00082434-03
> > >   b304         6086656 mmcblk0p4 00082434-04
> > > Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
> > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted
> > > 3.17.0-rc2-00368-gec0400b-dirty #83
> > >
> > >
> > > What is going on there? Clearly partition table was parsed and
> > > partitions are available; does the mention of unknown-block(0,0) mean
> > > that kernel failed to parse the command line?
> > >
> > > I replaced "root=/dev/mmcblk0p2" with "root=b302" and have a booting
> > > system.
> > 
> > 
> > Can you do a bisect? 3.17-rc2 booted fine for me today:
> > 
> > EXT3-fs (mmcblk0p2): mounted filesystem with ordered data mode
> > VFS: Mounted root (ext3 filesystem) on device 179:2.
> > Freeing unused kernel memory: 252K (c052d000 - c056c000)
> > random: nonblocking pool is initialized
> 
> Bisect would be hard... and I believe the problem is somewhere in
> block layer now -- not socfpga-specific.

[Adding those on the commit mentioned below to this thread.]

I just updated my nightly build system from -rc3 to -rc5, and I'm seeing
this on the LDP3430 platform (but not the SDP4430) despite both using
MMC rootfs.

On SD4430, I see:

Kernel command line: root=/dev/mmcblk0p2 rw mem=512M vmalloc=1G console=ttyO2,115200n8 rootdelay=2 debug
...
mmc0: new high speed SD card at address 0002
mmcblk0: mmc0:0002 00000 971 MiB
 mmcblk0: p1 p2
leds_pwm pwmleds: unable to request PWM for omap4:green:chrg: -517
platform pwmleds: Driver leds_pwm requests probe deferral
Waiting 2 sec before mounting root device...
mmc1: new high speed MMC card at address 0001
mmcblk1: mmc1:0001 SEM08G 7.39 GiB
mmcblk1boot0: mmc1:0001 SEM08G partition 1 1.00 MiB
mmcblk1boot1: mmc1:0001 SEM08G partition 2 1.00 MiB
 mmcblk1: unknown partition table
 mmcblk1boot1: unknown partition table
 mmcblk1boot0: unknown partition table
leds_pwm pwmleds: unable to request PWM for omap4:green:chrg: -517
platform pwmleds: Driver leds_pwm requests probe deferral
kjournald starting.  Commit interval 5 seconds
EXT3-fs (mmcblk0p2): warning: maximal mount count reached, running e2fsck is recommended
EXT3-fs (mmcblk0p2): using internal journal
EXT3-fs (mmcblk0p2): recovery complete
EXT3-fs (mmcblk0p2): mounted filesystem with writeback data mode
VFS: Mounted root (ext3 filesystem) on device 179:2.

However, on LDP3430:

Kernel command line: console=ttyO2,115200n8 noinitrd vmalloc=1G mem=128M root=/dev/mmcblk0p2 rw ip=none rootdelay=2 video=omap24xxfb:rotation=270
...
mmc0: host does not support reading read-only switch. assuming write-enable.
Waiting 2 sec before mounting root device...
mmc0: new high speed SD card at address 0002
mmcblk0: mmc0:0002 00000 971 MiB
 mmcblk0: p1 p2
VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
b300          994816 mmcblk0  driver: mmcblk
  b301           72261 mmcblk0p1 0b4c6c45-01
  b302          915705 mmcblk0p2 0b4c6c45-02
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

I think the problem may be 4dfe694f616e00e6fd83e5bbcd7a3c4d7113493d
("init: make rootdelay=N consistent with rootwait behaviour") which
was merged during the recent window.  This moved the delay after the
saved_root_name[] handling.  As we can see in the SDP4430 case, the
order was:

 - mmcblk0p2 detected
 - delay message
 - rootfs failure

and everything worked.  However, in the LDP3430 case:

 - delay message
 - mmcblk0p2 detected
 - rootfs failure

and it failed.  If we look at the code as it stands today:

        if (saved_root_name[0]) {
                root_device_name = saved_root_name;
                if (!strncmp(root_device_name, "mtd", 3) ||
                    !strncmp(root_device_name, "ubi", 3)) {
                        mount_block_root(root_device_name, root_mountflags);
                        goto out;
                }
                ROOT_DEV = name_to_dev_t(root_device_name);
                if (strncmp(root_device_name, "/dev/", 5) == 0)
                        root_device_name += 5;
        }

This tries to look up the root device name and translate to a dev_t.
We know that "mmcblk0p2" doesn't exist at this point, so ROOT_DEV is
zero here.

        if (initrd_load())
                goto out;

        if (root_delay) {
                pr_info("Waiting %d sec before mounting root device...\n",
                        root_delay);
                ssleep(root_delay);
        }

Here's our delay.

        /* 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);
                async_synchronize_full();
        }

If ROOT_DEV was still zero, and root_wait was set (it isn't) we'd then
try to re-evaluate ROOT_DEV.  ROOT_DEV must be set to mount the rootfs,
and we can see from the above failure messages that it was still zero.
That works out, because this code would never be run with root_wait=false.

The reason it used to work is because the delay came _before_ the first
"if" above, so causing the first ROOT_DEV lookup to succeed.

I think it may be better to move the root_delay handling either immediately
after md_run_setup(), or we need to re-lookup ROOT_DEV after the delay.
Paul, any thoughts?

-- 
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.

Re: 3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

[Russell King - ARM Linux]

On Wed, Sep 17, 2014 at 02:20:02PM +0100, Russell King - ARM Linux wrote:
> On Tue, Sep 09, 2014 at 01:49:41PM +0200, Pavel Machek wrote:
> > Bisect would be hard... and I believe the problem is somewhere in
> > block layer now -- not socfpga-specific.
> 
> [Adding those on the commit mentioned below to this thread.]
> 
> I just updated my nightly build system from -rc3 to -rc5, and I'm seeing
> this on the LDP3430 platform (but not the SDP4430) despite both using
> MMC rootfs.
> 
> On SD4430, I see:
> 
> Kernel command line: root=/dev/mmcblk0p2 rw mem=512M vmalloc=1G console=ttyO2,115200n8 rootdelay=2 debug
> ...
> mmc0: new high speed SD card at address 0002
> mmcblk0: mmc0:0002 00000 971 MiB
>  mmcblk0: p1 p2
> leds_pwm pwmleds: unable to request PWM for omap4:green:chrg: -517
> platform pwmleds: Driver leds_pwm requests probe deferral
> Waiting 2 sec before mounting root device...
> mmc1: new high speed MMC card at address 0001
> mmcblk1: mmc1:0001 SEM08G 7.39 GiB
> mmcblk1boot0: mmc1:0001 SEM08G partition 1 1.00 MiB
> mmcblk1boot1: mmc1:0001 SEM08G partition 2 1.00 MiB
>  mmcblk1: unknown partition table
>  mmcblk1boot1: unknown partition table
>  mmcblk1boot0: unknown partition table
> leds_pwm pwmleds: unable to request PWM for omap4:green:chrg: -517
> platform pwmleds: Driver leds_pwm requests probe deferral
> kjournald starting.  Commit interval 5 seconds
> EXT3-fs (mmcblk0p2): warning: maximal mount count reached, running e2fsck is recommended
> EXT3-fs (mmcblk0p2): using internal journal
> EXT3-fs (mmcblk0p2): recovery complete
> EXT3-fs (mmcblk0p2): mounted filesystem with writeback data mode
> VFS: Mounted root (ext3 filesystem) on device 179:2.
> 
> However, on LDP3430:
> 
> Kernel command line: console=ttyO2,115200n8 noinitrd vmalloc=1G mem=128M root=/dev/mmcblk0p2 rw ip=none rootdelay=2 video=omap24xxfb:rotation=270
> ...
> mmc0: host does not support reading read-only switch. assuming write-enable.
> Waiting 2 sec before mounting root device...
> mmc0: new high speed SD card at address 0002
> mmcblk0: mmc0:0002 00000 971 MiB
>  mmcblk0: p1 p2
> VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error -6
> Please append a correct "root=" boot option; here are the available partitions:
> b300          994816 mmcblk0  driver: mmcblk
>   b301           72261 mmcblk0p1 0b4c6c45-01
>   b302          915705 mmcblk0p2 0b4c6c45-02
> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
> 
> I think the problem may be 4dfe694f616e00e6fd83e5bbcd7a3c4d7113493d
> ("init: make rootdelay=N consistent with rootwait behaviour") which
> was merged during the recent window.  This moved the delay after the
> saved_root_name[] handling.  As we can see in the SDP4430 case, the
> order was:
> 
>  - mmcblk0p2 detected
>  - delay message
>  - rootfs failure
> 
> and everything worked.  However, in the LDP3430 case:
> 
>  - delay message
>  - mmcblk0p2 detected
>  - rootfs failure
> 
> and it failed.  If we look at the code as it stands today:
> 
>         if (saved_root_name[0]) {
>                 root_device_name = saved_root_name;
>                 if (!strncmp(root_device_name, "mtd", 3) ||
>                     !strncmp(root_device_name, "ubi", 3)) {
>                         mount_block_root(root_device_name, root_mountflags);
>                         goto out;
>                 }
>                 ROOT_DEV = name_to_dev_t(root_device_name);
>                 if (strncmp(root_device_name, "/dev/", 5) == 0)
>                         root_device_name += 5;
>         }
> 
> This tries to look up the root device name and translate to a dev_t.
> We know that "mmcblk0p2" doesn't exist at this point, so ROOT_DEV is
> zero here.
> 
>         if (initrd_load())
>                 goto out;
> 
>         if (root_delay) {
>                 pr_info("Waiting %d sec before mounting root device...\n",
>                         root_delay);
>                 ssleep(root_delay);
>         }
> 
> Here's our delay.
> 
>         /* 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);
>                 async_synchronize_full();
>         }
> 
> If ROOT_DEV was still zero, and root_wait was set (it isn't) we'd then
> try to re-evaluate ROOT_DEV.  ROOT_DEV must be set to mount the rootfs,
> and we can see from the above failure messages that it was still zero.
> That works out, because this code would never be run with root_wait=false.
> 
> The reason it used to work is because the delay came _before_ the first
> "if" above, so causing the first ROOT_DEV lookup to succeed.
> 
> I think it may be better to move the root_delay handling either immediately
> after md_run_setup(), or we need to re-lookup ROOT_DEV after the delay.
> Paul, any thoughts?

Having discussed this with Paul on irc, I came up with this patch which
solves the problem for me.

One thing remaining from this is a question about whether we should wait
for a rootfs which we already have discovered (iow, ROOT_DEV != 0).
That's a separate issue which I do not intend to address.

8<====
From: Russell King <rmk+kernel@arm.linux.org.uk>
Subject: [PATCH] Fix rootdelay wait causing rootfs mount failure

Using rootdelay in recent kernels causes the rootfs to fail if the
device being waited for appears during the wait.  The problem is that
ROOT_DEV is not re-looked up after the wait expires, meaning that
ROOT_DEV is zero.  This leads to failures such as:

  mmc0: host does not support reading read-only switch. assuming write-enable.
  Waiting 2 sec before mounting root device...
  mmc0: new high speed SD card at address 0002
  mmcblk0: mmc0:0002 00000 971 MiB
   mmcblk0: p1 p2
  VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error -6
  Please append a correct "root=" boot option; here are the available partitions:
  b300          994816 mmcblk0  driver: mmcblk
    b301           72261 mmcblk0p1 0b4c6c45-01
    b302          915705 mmcblk0p2 0b4c6c45-02
  Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

Fix this by re-looking up the ROOT_DEV after the delay wait.

Fixes: 4dfe694f616e ("init: make rootdelay=N consistent with rootwait behaviour")
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 init/do_mounts.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/init/do_mounts.c b/init/do_mounts.c
index b6237c31b0e2..1353f607b374 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -569,6 +569,8 @@ void __init prepare_namespace(void)
 		pr_info("Waiting %d sec before mounting root device...\n",
 			root_delay);
 		ssleep(root_delay);
+		/* Re-evaluate the root name to get the dev_t */
+		ROOT_DEV = name_to_dev_t(saved_root_name);
 	}
 
 	/* wait for any asynchronous scanning to complete */


-- 
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.

Re: 3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

[Paul Gortmaker]

[Re: 3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails] On 17/09/2014 (Wed 14:20) Russell King - ARM Linux wrote:

[...]

> I think the problem may be 4dfe694f616e00e6fd83e5bbcd7a3c4d7113493d
> ("init: make rootdelay=N consistent with rootwait behaviour") which
> was merged during the recent window.  This moved the delay after the
> saved_root_name[] handling.  As we can see in the SDP4430 case, the
> order was:

[...]

> 
> 
> If ROOT_DEV was still zero, and root_wait was set (it isn't) we'd then
> try to re-evaluate ROOT_DEV.  ROOT_DEV must be set to mount the rootfs,
> and we can see from the above failure messages that it was still zero.
> That works out, because this code would never be run with root_wait=false.
> 
> The reason it used to work is because the delay came _before_ the first
> "if" above, so causing the first ROOT_DEV lookup to succeed.
> 
> I think it may be better to move the root_delay handling either immediately
> after md_run_setup(), or we need to re-lookup ROOT_DEV after the delay.
> Paul, any thoughts?

After discussing it more on irc, it seems like moving the delay/wait
handling after md_run_setup [i.e. to the original location of delay vs.
the original location of wait] is probably best.

But, given as the original commit log indicated -- there may be a risk
of other corner cases subtly being broken by such a change, it is
probably best if we just revert the original now, and then try again in
the alternate location in the next dev cycle.  I'll send a revert
shortly.

Thanks for diagnosing this.
Paul.
--

> 
> -- 
> FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
> according to speedtest.net.

[PATCH] Revert "init: make rootdelay=N consistent with rootwait behaviour"

[Paul Gortmaker]

This reverts commit 4dfe694f616e00e6fd83e5bbcd7a3c4d7113493d.

In that, we did:

  Here we move the rootdelay code to be right beside the rootwait code, so
  that their behaviour is consistent.

...which is fine, but in hindsight, perhaps moving the rootwait to be
beside the rootdelay would have been better.  We also indicated:

  It should be noted that in doing so, the actions based on the
  saved_root_name[0] and initrd_load() were previously put on hold by
  rootdelay=N and now currently will not be delayed.  However, I think
  consistent behaviour is more important than matching historical behaviour
  of delaying the above two operations.

But Pavel reported an instance where an ARM target with root on MMC
was failing to mount root, and Russell diagnosed it to the fact that
the call to set ROOT_DEV within the saved_root_name[0] processing
block mentioned above was no longer being delayed.

Rather than moving both wait clauses to the original position of
rootdelay and risking unearthing other possible corner case breakage
at this point in time, we simply revert now and we can revisit
trying the alternate/earlier location in another development cycle.

Cc: Pavel Machek <pavel@denx.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/init/do_mounts.c b/init/do_mounts.c
index b6237c31b0e2..82f22885c87e 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -539,6 +539,12 @@ void __init prepare_namespace(void)
 {
 	int is_floppy;
 
+	if (root_delay) {
+		printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
+		       root_delay);
+		ssleep(root_delay);
+	}
+
 	/*
 	 * wait for the known devices to complete their probing
 	 *
@@ -565,12 +571,6 @@ void __init prepare_namespace(void)
 	if (initrd_load())
 		goto out;
 
-	if (root_delay) {
-		pr_info("Waiting %d sec before mounting root device...\n",
-			root_delay);
-		ssleep(root_delay);
-	}
-
 	/* wait for any asynchronous scanning to complete */
 	if ((ROOT_DEV == 0) && root_wait) {
 		printk(KERN_INFO "Waiting for root device %s...\n",
-- 
1.9.2

Re: [PATCH] Revert "init: make rootdelay=N consistent with rootwait behaviour"

[Pavel Machek]

On Wed 2014-09-17 10:57:45, Paul Gortmaker wrote:
> This reverts commit 4dfe694f616e00e6fd83e5bbcd7a3c4d7113493d.

This solves my problems, thanks.

Tested-by: Pavel Machek <pavel@denx.de>

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

rootdelay regression is back in 4.0? was Re: [PATCH] Revert "init: make rootdelay=N consistent with rootwait behaviour"

[Pavel Machek]

On Thu 2014-09-18 15:17:16, Pavel Machek wrote:
> On Wed 2014-09-17 10:57:45, Paul Gortmaker wrote:
> > This reverts commit 4dfe694f616e00e6fd83e5bbcd7a3c4d7113493d.
> 
> This solves my problems, thanks.

Weird. It seems this regression is back in 4.0-rc7?

root=0xb302 works, root=/dev/mmcblk0p2 does not. socfpga board.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html