Kernel boot panic

Kernel boot panic

[Amit Mahadik]

? ? ?Hi,? ? ? I am trying to boot Linux kernel version 4.4.16 on custom ARM based development platform.I want to separate rootfs and kernel Image so that the size of my uImage is small. I followed the following steps.
1. Partitioned the SD card. It has 2 partition. First partition is formatted as vfat partition and ? ?has uImage (without rootfs). Second partition is formatted as ext3 and has the rootfs.2. I then changed the U-Boot (version 2011.05) bootargs? ?Kernel command line: console=ttyS0,115200 noinitrd rw rootfstype=ext3 root=/dev/mmcblk0p2 ? ? ? ? ?rootwait mem=512M coherent_pool=4M no_console_suspend resume=/dev/mtdblock3.

However, while booting I get the following error?
Failed to create /dev/root: -2VFS: Cannot open root device "mmcblk0p2" or unknown-block(179,2): error -2
I have also attached log for reference.?Can anyone please point out what I may be missing?
Regards,Amit.
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Kernel boot panic

[Amit Mahadik]

Hi Valdis,? ? ? ? ? ? ? ?Thanks for your prompt answer. I have ext3 builtin the kernel. After looking into the code I found that sys_mknod function fails. I am unable to understand why this happens?
Regards,Amit. 

    On Wednesday, 30 November 2016 11:38 PM, "Valdis.Kletnieks at vt.edu" <Valdis.Kletnieks@vt.edu> wrote:
 

 On Wed, 30 Nov 2016 14:12:18 +0000, Amit Mahadik said:

> bootargs? ?Kernel command line: console=ttyS0,115200 noinitrd rw rootfstype=ext3 root=/dev/mmcblk0p2 ? ? ? ? ?rootwait mem=512M coherent_pool=4M no_console_suspend resume=/dev/mtdblock3.

> However, while booting I get the following error?
> Failed to create /dev/root: -2VFS: Cannot open root device "mmcblk0p2" or unknown-block(179,2): error -2

If you're booting with noinitrd, you better have ext3 as a builtin, not a
module, or you're going to have a really bad day....




   
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Kernel boot panic

[Amit Mahadik]

? ? ?Hi,
? ? ? I am trying to boot Linux kernel version 4.4.16 on custom ARM based development platform.I want to separate rootfs and kernel Image so that the size of my uImage is small. I followed the following steps.
1. Partitioned the SD card. It has 2 partition. First partition is formatted as vfat partition and ? ?has uImage (without rootfs). Second partition is formatted as ext3 and has the rootfs.2. I then changed the U-Boot (version 2011.05) bootargs? ?Kernel command line: console=ttyS0,115200 noinitrd rw rootfstype=ext3 root=/dev/mmcblk0p2 ? ? ? ? ?rootwait mem=512M coherent_pool=4M no_console_suspend resume=/dev/mtdblock3.

However, while booting I get the following error?
Failed to create /dev/root: -2VFS: Cannot open root device "mmcblk0p2" or unknown-block(179,2): error -2
I have also attached log for reference.?Can anyone please point out what I may be missing?
Regards,Amit.


   
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Kernel boot panic

[Kristof Provost]

On 8 Dec 2016, at 15:59, Amit Mahadik wrote:
> ? ? ?Hi,
> ? ? ? I am trying to boot Linux kernel version 4.4.16 on custom ARM 
> based development platform.I want to separate rootfs and kernel Image 
> so that the size of my uImage is small. I followed the following 
> steps.
> 1. Partitioned the SD card. It has 2 partition. First partition is 
> formatted as vfat partition and ? ?has uImage (without rootfs). 
> Second partition is formatted as ext3 and has the rootfs.2. I then 
> changed the U-Boot (version 2011.05) bootargs? ?Kernel command line: 
> console=ttyS0,115200 noinitrd rw rootfstype=ext3 root=/dev/mmcblk0p2 
> ? ? ? ? ?rootwait mem=512M coherent_pool=4M no_console_suspend 
> resume=/dev/mtdblock3.
>
> However, while booting I get the following error?
> Failed to create /dev/root: -2VFS: Cannot open root device "mmcblk0p2" 
> or unknown-block(179,2): error -2
> I have also attached log for reference.?Can anyone please point out 
> what I may be missing?

Well, your kernel finds the partition, but it?s still unable to open 
the root device.
Did you remember to compile ext3 support into your kernel (so not as a 
module)?

Regards,
Kristof

Kernel boot panic

[Amit Mahadik]

Hi Kristof,? ? ? ? ? ? ? ?Yes I have compiled the EXT3 support into the kernel itself. But no luck yet!
Regards,Amit. 

    On Thursday, 8 December 2016 10:51 PM, Kristof Provost <kristof@sigsegv.be> wrote:
 

 On 8 Dec 2016, at 15:59, Amit Mahadik wrote:
> ? ? ?Hi,
> ? ? ? I am trying to boot Linux kernel version 4.4.16 on custom ARM 
> based development platform.I want to separate rootfs and kernel Image 
> so that the size of my uImage is small. I followed the following 
> steps.
> 1. Partitioned the SD card. It has 2 partition. First partition is 
> formatted as vfat partition and ? ?has uImage (without rootfs). 
> Second partition is formatted as ext3 and has the rootfs.2. I then 
> changed the U-Boot (version 2011.05) bootargs? ?Kernel command line: 
> console=ttyS0,115200 noinitrd rw rootfstype=ext3 root=/dev/mmcblk0p2 
> ? ? ? ? ?rootwait mem=512M coherent_pool=4M no_console_suspend 
> resume=/dev/mtdblock3.
>
> However, while booting I get the following error?
> Failed to create /dev/root: -2VFS: Cannot open root device "mmcblk0p2" 
> or unknown-block(179,2): error -2
> I have also attached log for reference.?Can anyone please point out 
> what I may be missing?

Well, your kernel finds the partition, but it?s still unable to open 
the root device.
Did you remember to compile ext3 support into your kernel (so not as a 
module)?

Regards,
Kristof

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Kernel boot panic

[Kristof Provost]

On 12 Dec 2016, at 9:53, Amit Mahadik wrote:
> Yes I have compiled the EXT3 support into the kernel itself. But no 
> luck yet!
> Regards,Amit.
>
Have you tried mounting the ext3 partition in another linux machine?  
Your log
indicates the kernel is not able to mount the partition, so the most 
likely
causes are that the kernel doesn?t know how to read ext3 or that 
there?s no
ext3 there.

Regards,
Kristof

Kernel boot panic

[Amit Mahadik]

Hi Kristof,????????????? Yes I tried mounting the SD card on another Linux machine. I can mount it. Following is its log*********************************************************************************************************************************************************************************root at sagark-Ubu14:~/amitm# mount
/dev/sda1 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
none on /sys/fs/pstore type pstore (rw)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
systemd on /sys/fs/cgroup/systemd type cgroup (rw,noexec,nosuid,nodev,none,name=systemd)
/dev/sdb1 on /media/evslab/BOOT type vfat (rw,nosuid,nodev,uid=1001,gid=1001,shortname=mixed,dmask=0077,utf8=1,showexec,flush,uhelper=udisks2)
/dev/sdb2 on /mnt type ext3 (rw)**************************************************************************************************************************************************************************************
I have created the ROOTFS image using buildroot 2016.05 version. The /dev management option selected is "Dynamic using devtmpfs + eudev" and corresponding DEVTMPS options are enabled in Kernel config. 

Browsing through the kernel code I find that the code gives error after create_dev API in init/do_mounts.c file. 

Please let me know what I am doing wrong or missing?
Regards,Amit.
 

    On Monday, 12 December 2016 2:38 PM, Kristof Provost <kristof@sigsegv.be> wrote:
 

 On 12 Dec 2016, at 9:53, Amit Mahadik wrote:
> Yes I have compiled the EXT3 support into the kernel itself. But no 
> luck yet!
> Regards,Amit.
>
Have you tried mounting the ext3 partition in another linux machine?? 
Your log
indicates the kernel is not able to mount the partition, so the most 
likely
causes are that the kernel doesn?t know how to read ext3 or that 
there?s no
ext3 there.

Regards,
Kristof

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Kernel boot panic

[Kristof Provost]

Please don?t top-post.

On 12 Dec 2016, at 10:59, Amit Mahadik wrote:
> Yes I tried mounting the SD card on another Linux machine. I can mount 
> it. Following is its 
> log*********************************************************************************************************************************************************************************root at sagark-Ubu14:~/amitm# 
> mount
> /dev/sda1 on / type ext4 (rw,errors=remount-ro)
> proc on /proc type proc (rw,noexec,nosuid,nodev)
> devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
> tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
> none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
> none on /run/shm type tmpfs (rw,nosuid,nodev)
> none on /run/user type tmpfs 
> (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
> none on /sys/fs/pstore type pstore (rw)
> binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc 
> (rw,noexec,nosuid,nodev)
> systemd on /sys/fs/cgroup/systemd type cgroup 
> (rw,noexec,nosuid,nodev,none,name=systemd)
> /dev/sdb1 on /media/evslab/BOOT type vfat 
> (rw,nosuid,nodev,uid=1001,gid=1001,shortname=mixed,dmask=0077,utf8=1,showexec,flush,uhelper=udisks2)
> /dev/sdb2 on /mnt type ext3 
> (rw)**************************************************************************************************************************************************************************************
> I have created the ROOTFS image using buildroot 2016.05 version. The 
> /dev management option selected is "Dynamic using devtmpfs + eudev" 
> and corresponding DEVTMPS options are enabled in Kernel config.
>
Oooh, I missed this in the log the first time round:

	[    6.227066] Failed to create /dev/root: -2?

This is logged by `mount_root()`, if the `create_dev()` call fails.
It returned -2, which is `-ENOENT`.

Does your rootfs have a /dev directory?

Regards,
Kristof
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