user626201's questions

We are developing an embedded device that runs on Linux and uses NFS mounts to aid in development. We are working in two private network spaces (172.16.x.y and 192.168.0.n). The 192 network contains 40Mb/s multicast traffic that the device needs, but in order not to swamp the 172 network the network traffic is generated by a Windows 2008 R2 Server. The Windows Server 2008 box has 2 NICs - one for 192 (generated from the DHCP server on it) and one for 172 network (the default gateway on the Windows box points to the 172 gateway)

In our development environment we have the following connections:

Device 172.16.50.100 (static)]----[Gateway (172.16.15.200)]----[Ubuntu Linux Server 172.16.10.100]

The device is able to mount and execute code on the 172.16.10.100 server.

However, when we move the device to the Windows Server network:

Device 192.168.0.2(dhcp)]---[Server 2008 (192.16.0.1)(dhcp server) NIC2(172.16.50.200)]---[Ubuntu Linux Server 172.16.10.100]

Now the device is unable to mount the NFS directories:

\$ mount -t nfs 172.16.10.100:<path> hd
mount: 172.16.10.100:<path> failed, reason given by server: Permission denied
mount: mounting 172.16.10.100:<path> on hd failed: Bad file descriptor

We can ping the server:

\$ ping -c 1 172.16.10.100
PING 172.16.10.100 (172.16.10.100): 56 data bytes
64 bytes from 172.16.10.100: seq=0 ttl=64 time=1.231 ms

--- 172.16.10.100 ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 1.231/1.231/1.231 ms

Hence the device can see the Ubuntu server fine when it is on the 192 network, but is unable to mount the NFS.

We have disabled the Windows Server 2008 Firewall as well.

How do we get the NFS data to pass through the server?

Thanks.

Our Linux kernel is 2.6.31 running on an embedded MIPS processor with busybox.

The initialisation script (rcS) starts mdev with:

echo "/sbin/stbhotplug" > /proc/sys/kernel/hotplug
mdev -s

Can anyone tell me what the Linux utility mdev does?

It looks like it does auto hot plugging as the stbhotplug is a script that handle ethernet interfaces.

Also, the rootfs we have been given only has a console device i.e. /dev/console is the only file in /dev.

However, when the system is running, the /dev directory is full of device files (e.g. /dev/mtd, etc.).

The reason I ask is that occasionally we get an error whereby it is reported that /dev/ubi_ctrl is not found or /dev/ubi1 is not found.

How or when does Linux create these devices?

Thanks.