# Boot to new kernel gives "No NFS servers avail" [SOLVED]

## mwace

I'm trying to update my kernel from 2.6.25-gentoo-r7 to 2.6.31-gentoo-r6. My partition layout is:

/dev/sda1 --- ntfs data partition

/dev/sda2 --- swap

/dev/sda3 --- ext2 boot partition

/dev/sda4 --- reiserfs gentoo partition

When I boot up the new kernel, I have the output [dictated from the screen]:

```
Root-NFS: No NFS server available, giving up.

VFS: Unable to mount root fs via NFS, trying floppy.

VFS: Cannot open root device "sda4" or unknown-block(2,0)

Please append a correct "root=" boot option; here are the available partitions:

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown block(2,0)

Pid 1, comm: swapper Not tainted 2.6.31-gentoo-r6 #2

Call trace:

[*nonsense*] panic+0ax0/0x14b

[*nonsense*] ? printk_all_partitions+0x1de/0x1f0

[*nonsense*] ? sys_mount+0xab/0xc1

[*nonsense*] mount_block_root+0x1d3/0x1ea

[*nonsense*] mount_root+0x79/0x99

[*nonsense*] prepare_namespace+0x170/0x19d

[*nonsense*] kernel_init+0x1a3/0x1b3

[*nonsense*] child_rip+0xa/0x20

[*nonsense*] ? kernel_init+0x0/0x1b3

[*nonsense*] ? child_rip+0x0/0x20
```

A second boot option in grub.conf contains the identical kernel line with the kernel name revised to 2.5.25-gentoo-r7_mwace, and is completely functional. The grub.conf kernel line reads:

```
kernel /boot/kernel_linux-2.6.31-gentoo-r6_mwace root=/dev/sda4
```

I have rerun 'grub-install --no-floppy /dev/sda' with the boot partition mounted, configured my kernel and emerged the package in this howto, and ensured that the reiserfs support is included within the kernel.  However, this error is persisting.

Here is my /etc/mtab, which is used during grub-install and may have a bearing on my machine's difficulty with mounting the root partition (/dev/sda4):

```
dev/sda4 / reiserfs rw,noatime 0 0

proc /proc proc rw,nosuid,nodev,noexec 0 0

sysfs /sys sysfs rw,nosuid,nodev,noexec 0 0

udev /dev tmpfs rw,nosuid,size=10240k,mode=755 0 0

devpts /dev/pts devpts rw,nosuid,noexec,gid=5,mode=620 0 0

/dev/sda1 /home/mwace/Compositions ntfs rw,noatime 0 0

/dev/sdb1 /home/mwace/Collections ntfs rw,noatime 0 0

shm /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0

usbfs /proc/bus/usb usbfs rw,noexec,nosuid,devmode=0664,devgid=85 0 0

nfsd /proc/fs/nfsd nfsd rw,noexec,nosuid,nodev 0 0

/dev/sda3 /boot ext3 rw 0 0
```

Last edited by mwace on Thu Mar 04, 2010 1:01 am; edited 4 times in total

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## muhsinzubeir

 *Quote:*   

> kerenel /boot/kernel_linux-2.6.31-gentoo-r6_mwace root=/dev/sda4

 

Hopefully thats a typo, but I am not sure if its only during posting on the forum or?

P:S

**I am getting confused btwn NFS that appeared on the error, and filesystem to boot your system whereby one is NTFS.These are 2 different fs, so the error is kinda confusing to me.  :Sad: 

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## mwace

 *muhsinzubeir wrote:*   

>  *Quote:*   kerenel /boot/kernel_linux-2.6.31-gentoo-r6_mwace root=/dev/sda4 
> 
> Hopefully thats a typo, but I am not sure if its only during posting on the forum or?
> 
> P:S
> ...

 

That was a typo on the forum and reads "kernel" grub.conf, I've edited the post to reflect this (I'm typing on a netbook).

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## mwace

Here is my /etc/mtab, which is used during grub-install and may have a bearing on my machine's difficulty with mounting the root partition (/dev/sda4):

```
dev/sda4 / reiserfs rw,noatime 0 0

proc /proc proc rw,nosuid,nodev,noexec 0 0

sysfs /sys sysfs rw,nosuid,nodev,noexec 0 0

udev /dev tmpfs rw,nosuid,size=10240k,mode=755 0 0

devpts /dev/pts devpts rw,nosuid,noexec,gid=5,mode=620 0 0

/dev/sda1 /home/mwace/Compositions ntfs rw,noatime 0 0

/dev/sdb1 /home/mwace/Collections ntfs rw,noatime 0 0

shm /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0

usbfs /proc/bus/usb usbfs rw,noexec,nosuid,devmode=0664,devgid=85 0 0

nfsd /proc/fs/nfsd nfsd rw,noexec,nosuid,nodev 0 0

/dev/sda3 /boot ext3 rw 0 0
```

Original post has been revised to include this.

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## jburns

You are missing the driver for your disk or the SCSI routines that support accessing the disk.  Check your .config file.

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## mwace

 *jburns wrote:*   

> You are missing the driver for your disk or the SCSI routines that support accessing the disk.  Check your .config file.

 

I rebuilt my kernel with very many of the SCSI device support options enabled in the Device Drivers section in menuconfig and my boot error remains unchanged. I don't understand what .config file in my boot partition would contain SCSI drivers or routines or how to include or edit them.

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## jburns

You should have 

```
CONFIG_SCSI=y

CONFIG_SCSI_DMA=y

CONFIG_SCSI_PROC_FS=y

CONFIG_BLK_DEV_SD=y
```

The drivers for your disk drives should be built into the kernel and not as modules.

You could do a diff between the .config of the working kernel and the new kernel to see what changed.

Edit:

The .config file is in /usr/src/linux*

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## mwace

 *jburns wrote:*   

> You should have 
> 
> ```
> CONFIG_SCSI=y
> 
> ...

 

Thanks for explaining the .config, I wasn't aware of that file. Your recommended configurations have been set.

I did a 'diff *2.6.25* *2.6.31* | grep SCSI' and meticulously replicated every enabled kernel option found in my 2.6.25 .config within my 2.6.31 config but it hasn't changed the boot output. I've also generally perused the kernel configuration a fair bit and the any misconfigurations don't appear obvious to me.

I am entertaining the idea of a hardware problem at the moment, but given how 2.6.25 works when 2.6.31 doesn't I ultimately should be able to get 2.6.31 working as well..

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## mwace

 *mwace wrote:*   

> I am entertaining the idea of a hardware problem at the moment, but given how 2.6.25 works when 2.6.31 doesn't I ultimately should be able to get 2.6.31 working as well..

 

I've eliminated hardware as a possible cause.

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## mwace

VICTORY

I did the same meticulous .config edit using diff output, only this time I grep'd SATA instead of SCSI. I can now boot the 2.6.31-gentoo-r6 kernel.

----------

