[Buildroot] proc not mouning

Heyendal, Carl CHeyendal at stanleyworks.com
Wed Mar 23 20:35:16 UTC 2011

> -----Original Message-----
> From: buildroot-bounces at busybox.net [mailto:buildroot-
> bounces at busybox.net] On Behalf Of Heyendal, Carl
> Sent: March 23, 2011 3:03 PM
> To: buildroot at busybox.net
> Subject: [Buildroot] proc not mouning
> Hi,
> I've done something bad to my Buildroot platform, but I can't figure
> out what the problem is.
> When the initramfs system switches over to the root filesystem on an SD
> Card created by Buildroot,
> it can't find /dev/null, and can't mount /proc.
> When I login the /proc directory is not mounted, but I can manually
> mount it however from the command
> line.
> My inittab contains a statement to mount proc as well as another
> statement to do a 'mount -a'.
> I verified that fstab contains an entry for proc. I know something is
> processing inittab because
> the boot scripts that inittab calls do run.
> I even added an entry in inittab to 'mknod' /dev/null.
> I'm really stumped by this. I even did a clean rebuild without any
> luck.
> Output below. Appreciate any help.
> thanx
> /carl h.
> mmc0: host does not support reading read-only switch. assuming write-
> enable.
> mmc0: new SD card at address aaaa
> mmcblk0: mmc0:aaaa SD02G 1.84 GiB
>  mmcblk0: p1
> EXT3-fs: barriers not enabled
> kjournald starting.  Commit interval 5 seconds
> EXT3-fs (mmcblk0p1): using internal journal
> EXT3-fs (mmcblk0p1): recovery complete
> EXT3-fs (mmcblk0p1): mounted filesystem with ordered data mode
> Switching to filesystem on SD card....
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> grep: /proc/mounts: No such file or directory
> grep: /proc/mounts: No such file or directory
> Populating /dev using udev: /etc/init.d/S10udev: line 82: can't create
> /proc/sys/kernel/hotplug: nonexistent directory
> done
> Starting portmap: done
> Initializing random number generator... done.
> Starting network...
> ifup: interface lo already configured
> ifup: interface eth0 already configured
> Starting ProFTPD: warning: `proftpd' uses 32-bit capabilities (legacy
> support in use)
>  - warning: unable to determine IP address of '_none_'
>  - error: no valid servers configured
>  - Fatal: error processing configuration file '/etc/proftpd.conf'
> Starting sshd: OK
> Welcome to Buildroot
> (none) login:
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Interestingly I solved the problem.

I was originally generating the root filesystem as a cpio archive and using that 
to populate my SD card. Later on, as a build optimization, I disabled generating 
rootfs.cpio at the top level Buildroot menuconfig. Instead I started copying 
'output/target/*' over to my SD card. That's when the trouble began I guess. I 
switched back to using rootfs.cpio to populate the SD card and I no longer have the 
problem. :-)

I've been dinged by not using cpio formats before, but had forgotten. What is it 
about cpio keeping filesystem archives sane when you copy them to other media? 
Why can't I just 'cp' the entire filesystem over as root?

Thanks Andy for your attention.



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