Re: [Ltib] udhcpc gets different addr

[Stuart Hughes]

Hi Michael,

You can do what you're trying to do without this patch, but it does need 
a config change.  Here's what's happening:

In the BSP you have, the config is probably setup to use dhcp to get the 
IP address.  You can verify this by running ./ltib -m config and 
checking in:  Target System Configuration / Network setup /
If the option: "get network parameters using dhcp" is checked then the 
network rc script will call ucdhcp.  The problem you're runing into 
happens to me, that is if I use NFS deployment and forget to set the IP 
address to something static, then I get a load of "rpc 101..." as the IP 
address from dhcpd is different to the one the kernel got.  I guess this 
maybe a bug in udhcpcd, not really sure.

I quite like your solution.  I think though it might be possible to 
improve it.  Rather than having to disable the network interface, it 
could be left on and in the network script you can test the deployment 
style and if it's NFS and dhcp is enabled, it could use your method 
instead to get the correctly assigned dynamic IP that the kernel has. 
The nice thing about this is it means you don't have to fiddle around 
with the configuration of the image, which means both jffs2 and NFS work 
without re-build/changes.

If you get what I mean maybe you could try this and send a patch? if not 
I could try to look at this when time permits.

Thanks for the patch.

Regards, Stuart

Michael Jones wrote:
> Hi LTIBbers,
>
> I have had the problem that I can't boot into the rootfs/ directory 
> using NFS if LTIB built "rootfs/" destined for a jffs2 image, because of 
> a problem with DHCP.  I can only use NFS if I tell LTIB that I want 
> Target image: "NFS only".  But I would like to be able to always build 
> the jffs2 image and still have the option of mounting via NFS.
>
> Here's the problem:  in my kernel config, I have CONFIG_IP_PNP_BOOTP=y. 
> This is necessary for NFS to work, to get an IP address before trying to 
> mount the root FS.  After mounting rootfs/, if DEPLOYMENT_STYLE is 
> anything but "NFS", udhcp is called to get an IP.  Because my kernel 
> config already got me an IP, this should just be a (safe) redundant 
> step, but for some reason, my DHCP server gives me a _different_ IP 
> address than I was given during kernel boot.  As soon as my IP changes, 
> my NFS is of course hosed.
>
> With the assurance that my kernel will take care of configuring the IP 
> address before mounting the RFS,  I'm unchecking "Enable interface 0" in 
> LTIB (SYSCFG_IFACE0=n), but then I get the misleading warning from 
> "/etc/rc.d/init.d/network" that "Warning: no IPADDR is set, ...".  I've 
> added the following patch below to my skell package so I don't get this 
> message unless "ifconfig" doesn't have an address for eth0.
>
> I don't mean to complain of a problem with LTIB here, because it seems 
> my DHCP server is misbehaving.  Does anybody have a suggestion why the 
> kernel DHCP and the udhcpc requests yield different addresses?  Do you 
> think my skell fix is hideous or problematic?
>
> thanks,
> Michael
>
>
> $ diff -u rpm/BUILD/skell-1.16/etc/rc.d/init.d/network 
> rootfs/etc/rc.d/init.d/network
> --- rpm/BUILD/skell-1.16/etc/rc.d/init.d/network        2007-06-18 
> 15:45:44.000000000 +0200
> +++ rootfs/etc/rc.d/init.d/network      2009-11-11 16:18:45.000000000 +0100
> @@ -24,7 +24,9 @@
>     #
>     # set up the network interfaces
>     #
> -    if [ "$IPADDR0" = "" ]
> +        ipaddr=`ifconfig eth0 | grep "\<inet addr\>" |\
> +                sed -e "s/^.*\<inet addr:\([0-9.]*\) .*/\1/"`;
> +    if [ "$IPADDR0" = "" ] && [ $ipaddr = "" ]
>     then
>         echo ""
>         echo "Warning: no IPADDR is set, please set this from the ltib"
>
>
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