Re: VFS: Cannot open root device "nfs" or unknown-block(0,255)

["Ibrahim Cihan SAHIN" <sahin.cihan@xxxxxxxxx>]

Hi all,

It has been a while but, the solution was pretty straight forward.

In linux configuration,

Networking Support ->Networking Options

Make sure the

<x> TCP/IP Networking

is enabled..

When you do that, another feature will be availabe under

File Systems - > Network File Systems
<x> Root File System on NFS

I tried after configuring the kernel as above, I was able to boot from NFS
with this command:

RedBoot> load -r -v -b 0x80000 zImage
Raw file loaded 0x00080000-0x001675a3, assumed entry at 0x00080000
RedBoot> exec -c "root=/dev/nfs nfsroot=<nfs-server-ip>:/nfsroot
ip=<target-ip>"


Another dipnot for NFS,

Before I was having a lot of problems with mounting a NFS directory. I was
able to do it but it was taking a lot of time (2mins) to mount a directory
and was giving me some warning messages like:

portmap: server localhost not responding, timed out
RPC: failed to contact portmap (errno -5).
portmap: server localhost not responding, timed out
RPC: failed to contact portmap (errno -5).
lockd_up: makesock failed, error=-5
portmap: server localhost not responding, timed out
RPC: failed to contact portmap (errno -5).

Since there is no portmap running on my target, it was trying to contact
portmap and I did not know where to disable this feature. But finally I
solved that problem by mounting with nolock option.

#>mount -t nfs -o nolock <nfs-server-ip>:/<exported-directory>
<target-directory>

It mounts right away...

I hope this thing might help others who have the same problems.

Cihan Sahin

cihan.sahin AT openvideoinc DOT com>
Jr. Firmware Engineer
Open Video Inc.
Aliso Viejo, CA
<http://www.openvideoinc.com/>
On 9/1/06, Abot Botbot <dejanigma@xxxxxxxxxxx> wrote:
> Cihan,
>
>    All my problems mounting NFS file systems were solved by updating my
> version of nfs-user-server on my linux machine. Perhaps this is your issue
> as well.
>
> Thanks,
> Andy
>
>
> >From: "Ibrahim Cihan SAHIN" < sahin.cihan@xxxxxxxxx>
> >To: linux-arm@xxxxxxxxxxxxxxxxxxxxxx
> >Subject: VFS: Cannot open root device "nfs" or unknown-block(0,255)
> >Date: Thu, 31 Aug 2006 15:01:35 -0700
> >
> >Hi all,
> >
> >I have a problem and I wanted to share my experiences. There maybe some
> >people who can help. My problem is with the booting process of my board
> >when
> >I want to use a remote NFS folder as my file system. I have followed the
> >isntructions on Documentation/nfsroot.txt step by step. However it looks
> >like my kernel does not recognize root=/dev/nfs virtual device file. The
> >details are below. Thanks in advance.
> >
> >When my linux 2.6 is running on my board, I can mount a directory on my
> >host
> >NFS server to directory on my target without any problem.
> >
> >My export file on my host looks like this :
> >
> >#/etc/exports
> >/root/workspace/nfsroot *(rw,sync,no_wdelay,no_root_squash)
> >
> >I have enabled NFS support on my kernel configuration. Here are the
> related
> >part of linux.config file
> >
> >#
> ># Network File Systems
> >#
> >CONFIG_NFS_FS=y
> >CONFIG_NFS_V3=y
> >CONFIG_NFS_V4=y
> >CONFIG_NFS_DIRECTIO=y
> >CONFIG_NFSD=y
> >CONFIG_NFSD_V3=y
> >CONFIG_NFSD_V4=y
> >CONFIG_NFSD_TCP=y
> >CONFIG_LOCKD=y
> >CONFIG_LOCKD_V4=y
> >CONFIG_EXPORTFS=y
> >CONFIG_SUNRPC=y
> >CONFIG_SUNRPC_GSS=y
> >CONFIG_RPCSEC_GSS_KRB5=y
> >
> >
> >Then what I do is to load the zImage to the flash memory from /tftpboot
> >directory and execute with kernel command line paremeters shwon below.
> >
> >RedBoot> load -r -v -b 0x80000 zImage
> >-
> >Raw file loaded 0x00080000-0x001652f3, assumed entry at 0x00080000
> >
> >RedBoot> exec -c "root=/dev/nfs rw
> >nfsroot=<nfsserver-ip>:/root/workspace/nfsroot ip=<target-ip>
> >console=ttyAM0,57600"
> >
> >Here is the output:
> >
> >Using base address 0x00080000 and length 0x000e52f4
> >Uncompressing
> >Linux................................................................
> done,
> >booting the kernel.
> >Linux version 2.6.8.1 (root@cihanbox) (gcc version 3.4.3) #1 Thu Aug 31
> >14:25:44 PDT 2006
> >CPU: ARM920Tid(wb) [41129200] revision 0 (ARMv4T)
> >CPU: D VIVT write-back cache
> >CPU: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
> >CPU: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
> >Machine: edb9302
> >Memory policy: ECC disabled, Data cache writeback
> >        bank 0 start at 0x00000000, length 0x00800000, mapped to
> 0xc0000000
> >        bank 1 start at 0x01000000, length 0x00800000, mapped to
> 0xc1000000
> >        bank 2 start at 0x04000000, length 0x00800000, mapped to
> 0xc4000000
> >        bank 3 start at 0x05000000, length 0x00800000, mapped to
> 0xc5000000
> >Built 1 zonelists
> >Kernel command line: root=/dev/nfs rw nfsroot=
> >10.3.130.18:/root/workspace/nfsroot ip= 10.3.130.14 console=ttyAM0,57600
> >PID hash table entries: 512 (order 9: 4096 bytes)
> >Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
> >Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
> >Memory: 8MB 8MB 8MB 8MB = 32MB total
> >Memory: 30216KB available (1761K code, 314K data, 64K init)
> >Calibrating delay loop... 99.73 BogoMIPS
> >Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
> >CPU: Testing write buffer coherency: ok
> >NET: Registered protocol family 16
> >devfs: 2004-01-31 Richard Gooch ( rgooch@xxxxxxxxxxxxx)
> >devfs: devfs_debug: 0x0
> >devfs: boot_options: 0x1
> >Installing knfsd (copyright (C) 1996 okir@xxxxxxxxxxxx).
> >Initializing Cryptographic API
> >ttyAM0 at MMIO 0x808c0000 (irq = 52) is a EP93XX
> >ttyAM1 at MMIO 0x808d0000 (irq = 54) is a EP93XX
> >RAMDISK driver initialized: 16 RAM disks of 16384K size 1024 blocksize
> >i2c /dev entries driver
> >NET: Registered protocol family 2
> >IP: routing cache hash table of 512 buckets, 4Kbytes
> >TCP: Hash tables configured (established 2048 bind 4096)
> >NET: Registered protocol family 1
> >NET: Registered protocol family 17
> >VFS: Cannot open root device "nfs" or unknown-block(0,255)
> >Please append a correct "root=" boot option
> >Kernel panic: VFS: Unable to mount root fs on unknown-block(0,255)
> >
> >
> >
> >For debugging, I have tried all versions of the kernel command line, such
>
> >as
> >"ip=on" , "ip=<target-ip>:<nfsserver-ip>" , etc..But what I figured out
> is
> >it is not even coming to the second parameter. It just does not like
> >"root=/dev/nfs" paremeter because even if I unplug the network cable from
>
> >the target it gives the same error which make me think that it is not a
> >connection problem with the nfs server. And as I already mentioned, I can
> >mount the nfs directory when my linux is running, that is another thing
> >which shows that there is not a problem on the connection with nfs server
> >in
> >my belief.
> >
> >Can anybody help me on that issue?  I saw similar threads on the web but
> >none of them has a clear solution. They just recommends to follow the
> steps
> >in nfsroot.txt documentation file which I already did a couple of times.
> >Any help is appreciated !
> >
> >Thanks,
> >
> >
> >Cihan Sahin
> ><cihan.sahin AT openvideoinc DOT com>
> >
> >Jr. Firmware Engineer
> >Open Video Inc.
> >Aliso Viejo, CA
> >http://www.openvideoinc.com
> >-------------------------------------------------------------------
> >List admin: http://lists.arm.linux.org.uk/mailman/listinfo/linux-arm
> >FAQ:         http://www.arm.linux.org.uk/mailinglists/faq.php
> >Etiquette:  http://www.arm.linux.org.uk/mailinglists/etiquette.php
>
> _________________________________________________________________
> Get real-time traffic reports with Windows Live Local Search
> http://local.live.com/default.aspx?v=2&cp=42.336065~-109.392273&style=r&lvl=4&scene=3712634&trfc=1
>
> <http://local.live.com/default.aspx?v=2&cp=42.336065%7E-109.392273&style=r&lvl=4&scene=3712634&trfc=1>
-------------------------------------------------------------------
List admin: http://lists.arm.linux.org.uk/mailman/listinfo/linux-arm
FAQ:        http://www.arm.linux.org.uk/mailinglists/faq.php
Etiquette:  http://www.arm.linux.org.uk/mailinglists/etiquette.php