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Old 03-02-2015, 03:25 AM   #1
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Basic networking in custom initramfs

I have made a custom initramfs with the absolute minimum files required and I have compiled a Centos 7 kernel for it with most of the drivers and options built in. The purpose is to have a minimal OS without switching to a real root and remain in an embedded environment. I need to run simple network applications with very little memory usage.
I used this site for reference :
The initramfs boots fine and I am able to use all the utilities using busybox. I have built the ethernet card drivers into the kernel and they are recognized.
When I give a static IP address to the network interface and try to ping my laptop directly connected to it, it doesn't work. Both systems are in the same subnet.
On further inspection using Wireshark I found that the ARP request coming out of my initramfs system is jumbled (the destination IP is in the wrong byte order). If I manually set the MAC addresses of the systems in each other's arp cache table, the ping is successful. This means that there is some problem with the MAC address resolution in the initramfs.
Does anyone have any suggestions?
Old 03-02-2015, 06:14 AM   #2
Keith Hedger
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You pobably need to ask this in the networking forum, ask a mod to move it for you
Old 03-02-2015, 06:32 AM   #3
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Alright, I've requested a switch to the Networking forum.
Old 03-02-2015, 07:14 AM   #4
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Moved: This thread is more suitable in Linux-Networkinig and has been moved accordingly to help your thread/question get the exposure it deserves.
Old 03-05-2015, 01:54 PM   #5
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Absolutely non-intuitive solution. I updated my kernel from 3.10.0-123.9.1.el7.x86_64 to 3.10.0-123.20.1.el7.x86_64 and compiled it with the same .config file. That solved the issue.
Note to self - Some problems have a straightforward solution. For all others, consider bashing your head on the keyboard until you chance upon it.


arp, embedded, initramfs, netwoking

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