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From: Ivo Grondman <>
Subject: [Buildroot] Handling delays in network interface visibility in Raspberry Pi 3
Date: Mon, 15 Feb 2021 17:34:14 +0100	[thread overview]
Message-ID: <> (raw)

Hi all,

Today I?ve been trying to debug the following issue. Using Buildroot 2020.11.2 and the Vagrantfile that comes with it, I tried to build a ?vanilla? Buildroot image in the vagrant VM for my Raspberry Pi 3 Model B+ in the following way:

$ make raspberrypi3_defconfig
$ make

i.e. without any customisation. The image builds fine and the Pi boots without errors or warnings, but the network interface eth0 (configured with DHCP) will not have an IPv4 address and I manually have to perform an `ifup -a` or `ifup eth0` to get it going. So I went through all the initialisation files that have a part in bringing up the network interface and soon came to conclude that the script in /etc/network/if-pre-up.d/wait_iface has the right intentions, but still doesn?t solve the slow-to-appear interface issue.

It looks as if that particular script still needs to wait just that bit longer when it sees that /sys/class/net/eth0 exists before actually exiting. Using the file as is will not make eth0 retrieve an address from the DHCP server, but if I add a bit of extra sleep in the if-statement where it detects the presence of /sys/class/net/eth0 then it *will* work.

Now my problem with this approach is that it feels like a hack. Moreover, I?d like to know if something else could be the issue here. So:

1) Did anyone of you experience similar issues with a Raspberry Pi?
2) Are there any alternative, better solutions to this problem?
3) If the answer to 2) is a ?no?, should I submit a patch for this particular script? I?m a bit hesitant to put in a patch with an extra delay on detection of the interface, as this is obviously not something you want to do for *all* possible platforms?

Any help is greatly appreciated.

Best regards,

Ivo Grondman

             reply	other threads:[~2021-02-15 16:34 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-15 16:34 Ivo Grondman [this message]
2021-02-15 18:26 ` [Buildroot] Handling delays in network interface visibility in Raspberry Pi 3 Nicolas Cavallari
2021-02-15 22:01 ` Peter Korsgaard
2021-02-16 10:37   ` Ivo Grondman
2021-02-16 11:23     ` Peter Korsgaard
2021-02-15 23:33 ` Christopher McCrory
2021-02-16 20:30   ` Peter Seiderer

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