General network freeze issue

[Thomas Goering]

Hi,

I noticed the same behavior on my Minix (3.3.0) installation in a VirtualBox VM (on my Mac, configured with a PCnet-FAST III (Am79C973) network adapter) and on my Thinkpad T420 (Intel 82540EP LP network adapter) and I am pretty sure they have the same root cause.

Virtual Box VM: If the network adapter is activated everything's fine. dhcpd gets a dynamic IP address, sshd starts successfully and I can ping any domain. But if I deactivate the network adapter and boot Minix, dhcp seems to time out after about 20 seconds with this message: "[5]    Alarm clock   intr -t 20 hosta...". This is not a big issue but after this any network access seems to freeze Minix. E.g. sshd doesn't start up (it hangs, freezes), or - if sshd is not automatically started - a simple ping freezes Minix.

Thinkpad T420: Here everything's fine as long as the ethernet cable is plugged. If the cable is not plugged in, it's the same as with the deactivated adapter in the Virtualbox VM: sshd and ping freeze.

An here's the thing: Although I cannot active the network adapter while the VM is running in Virtualbox, I can of course plug the ethernet cable into my Thinkpad while it is running. :-) And this seems to let dhcpd get a dynamic IP address in the background and thus sshd (haven't tested ping yes) continues after a couple of seconds!

Any idea what's the issue here and how this can be improved? My goal is to start Minix on my Thinkpad regardless of the ethernet cable being plugged in or not and without starting sshd starting manually! And currently this is not possible because sshd hangs if there's no ethernet cable plugged in.

Thomas

[Thomas Goering]

One addition: Of course I can abort (CTRL-C) ping and sshd (when started manually) but I haven't found a way to abort or set a timeout if sshd is started automatically on system boot.

Thomas

[Antoine LECA]

On 2014-12-12 15:46Z, Thomas Goering wrote:
> Virtual Box VM: If the network adapter is activated everything's fine.
> dhcpd gets a dynamic IP address, sshd starts successfully and I can ping
> any domain. But if I deactivate the network adapter and boot Minix, dhcp
> seems to time out after about 20 seconds with this message: "[5] Alarm
> clock intr -t 20 hosta...".

Yep this is long-standing known issue: you cannot boot Minix if you have
configured a network adapter to use DHCP, and the network is not
available (so no DHCP server will answer...)

Fact is the official answer is also long-standing, and reads something
as "we will ditch the old inet-server network code and its accompanying
dhcp to switch toward LWIP" [which is already committed in tree, just
not finished to debug.]

Meanwhile, the only answer I know of (besides putting the network on in
case it is just a disconnected cable) is to program the network manually
with a fixed IP; yes this is a pain.


Antoine

[Thomas Goering]

I set up the network with a fixed IP and it works. Thanks for your quick response.

Thomas