Re: [Ltib] udhcpc gets different addr

[Michael Jones]

Hi Stuart,

According to linux/Documentation/nfsroot.txt, you can just change the 
"ip=...eth0:off" part of your command line to "ip=...eth0:dhcp" or 
"ip=...eth0:bootp" (I'm using bootp).  You can also just replace the 
whole 'ip=...' part with just 'ip=dhcp' or 'ip=bootp'.

I'm using a version of RedBoot which annoyingly _always_ prepends the 
'ip' argument itself, filling in the addresses with RedBoot variables 
which I can set.  I can only choose between 'bootp' and 'off', and I 
can't use the nice, tidy, 'ip=dhcp' form.  In fact, maybe using bootp 
here has something to do with why my udhcpc gets a different IP address.

Also, you need kernel config options CONFIG_IP_PNP and e.g. 
CONFIG_IP_PNP_BOOTP enabled.

Glad to hear you like the suggestion :)

-Michael

Stuart Hughes wrote:
> Hi Michael,
>
> I like this suggestion and I'm trying to test it. However I need some 
> help.  Normally for NFS booting (u-boot),  I use the example line for 
> the boot args (all one line)
>
> => setenv bootargs root=/dev/nfs rw 
> nfsroot=192.168.0.10:/data/seh/Src/ltib_bsps/savannah_ltib/rootfs 
> ip=target_ip:192.168.0.10::255.255.255.0::eth0:off console=ttyS0,115200
>
> 192.168.0.10 is my NFS server.  Where I've written target_ip is where 
> I'd normally give a static IP address for the target.
>
> What's the correct kernel command line to say "dynamically get the 
> target IP address"?
>
> Regards, Stuart
>
> Michael Jones wrote:
> > 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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