Messages in this thread | | | Date | Fri, 23 Nov 2001 11:44:11 -0800 | From | Dave Ashley (linux mailing list) <> | Subject | bd_t structure + net configuration |
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I'm working on bringing up linux in an embedded environment, and the box is diskless and uses bootp to get its kernel + ramdisk. It uses ppcboot to get that information. We've modified ppcboot to pass more information to linux in the bd_t (board info) structure, specifically ip address netmask default gateway dns server hostname
The question is how to get linux to use this information? I couldn't find anything in the kernel source to do that. I had a temporary solution where linux invokes dhcpcd to get the information again, but the problem there is there are 2 dhcp servers on our network and the ip addresses assigned didn't match between the bootp stage and the dhcp stage later. And there is an efficiency problem--since the information is already in the box at the bootp time, why bother with dhcp later?
I was surprised to find no built in mechanism to configure networking from the boardinfo information.
Anyway what I ended up doing was modifying fs/proc/proc_misc.c to add a file /proc/boardinfo, which has the information visible. Then during booting, when networking would be initialized, I examine that file to know how to set everything up.
What I did was have the /proc/boardinfo file appear like an sh script, so when cat'd it looks like this: ifconfig eth0 192.168.0.20 netmask 255.255.255.0 route add default gw 192.168.0.75 echo nameserver 192.168.0.76 > /etc/resolv.conf hostname box1102
(The numbers here are just examples, they change depending on the bootp information).
I modified one of the startup scripts to configure networking: cat /proc/boardinfo > /tmp/bi sh /tmp/bi rm /tmp/bi
The only information used from the bd_t structure was the mac address of the ethernet card, originally. The bd_t structure appears as the global __res pointer.
I'm wondering if there is a prefered way of doing this? Also why does it seem like setting up networking from the bd_t structure hasn't been done before?
Thoughts? Comments? Anything welcome.
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