Re: [Ltib] udhcpc gets different addr

[Michael Jones]

Hi Stuart,

Now that I've got a hold of skell and merge, I've made some progress on 
this JFFS2/NFS DHCP problem...

Stuart Hughes wrote:
> 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.
Yes, my config was setup to use DHCP, so I first considered disabling 
this.  But I don't want to set a static IP address, either, since it was 
already configured by the kernel.  So I just disabled the whole section, 
"Enable Interface 0".  Admittedly, my LTIB config is then misleading, 
since it looks like eth0 is not enabled.
> 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. 
But it's this existing test for DEPLOYMENT_STYLE that's throwing me 
off.  Because I'm trying to get NFS to work even when 
DEPLOYMENT_STYLE="jffs2".  So really I'm trying to get NFS to work 
regardless of DEPLOYMENT_STYLE.

The patch below is my new suggestion.  I use 'mount' to determine if / 
is mounted on NFS and change DEPLOYMENT_STYLE to NFS if it is, which 
will then skip DHCP.  I think this achieves what you're suggesting.  I 
like it more than checking eth0's IP address because if it boots into 
jffs2, it will still do a udhcpc DHCP request like the user configured 
in LTIB. But...
* I'm unsure though whether my grep regex test for the mount rootfs line 
is appropriate in all cases.
* maybe you prefer checking for an existing IP address to decide whether 
or not to do DHCP?

diff --exclude CVS --exclude .git -uNr 
skell-1.16/etc/rc.d/init.d/network 
skell-1.16.modified/etc/rc.d/init.d/network
--- skell-1.16/etc/rc.d/init.d/network    2007-06-18 15:45:44.000000000 
+0200
+++ skell-1.16.modified/etc/rc.d/init.d/network    2009-11-18 
14:13:19.000000000 +0100
@@ -34,6 +34,15 @@
        sleep 2
    fi

+    # if rootfs is mounted via NFS, DEPLOYMENT_STYLE is NFS regardless
+    # whether LTIB built it for JFFS2.
+    rootmnt=`mount | grep "^/dev/root on / type" |\
+        sed -e "s/^.* type \([a-zA-Z0-9]*\).*/\1/"`;
+    if [ "$rootmnt" = "nfs" ]
+    then
+        DEPLOYMENT_STYLE=NFS;
+    fi
+
    if [ "$SYSCFG_IFACE0" = "y" ]
    then
        echo "Setting up networking on $INTERFACE0: "
> 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.
Yes, that's exactly what I'd like to achieve.  With the patch above it 
works like this for me.  I'm interested in your feedback.

thanks,
Michael
> 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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