netdev - Re: Commit "ipconfig wait for carrier" makes boot hang for 2 mins if no carrier

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Date:	Wed, 05 Sep 2012 10:30:36 +0200
From:	Micha Nelissen <micha@...i.hopto.org>
To:	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
CC:	netdev@...r.kernel.org
Subject: Re: Commit "ipconfig wait for carrier" makes boot hang for 2 mins
 if no   carrier

Op 2012-09-05 9:04, Joakim Tjernlund schreef:
>> Because that's where my root filesystem is? The IP autoconfiguration
>> code exists for this purpose.
>
> This is not the only purpose.

Documentation/filesystems/nfs/nfsroot.txt seems to suggest so (this is 
where the ip= parameter is documented), but it works independently indeed.

So explain your reasons?

>>> The answer is probably the same, it is much easier to
>>> manage our IP config in one place for our embedded system.
>>
>> You retrieve the kernel via TFTP or so when booting?
>
> Yes, but mostly not. This really doesn't matter

Seems to me that if you boot standalone there is no reason to let the IP 
address be configured by the kernel? Retrieve the IP address in user 
space from your bootloader environment or whatever. And if you boot from 
ethernet (or some other networking interface), then you have a carrier, 
and there is no 2 minute delay (maybe less even than before with this 
patch!).

>>> The wait should be conditional on NFS root or not so that non NFS roots
>>> can skip this stage altogether.
>
> Your patch broke other use cases so my patch would just revert or change the tmo
> to 2 secs or so.
> Or you could clean up your stuff so it works for all and not just for you.

It didn't break anything, it does work for you also, you just need to 
wait somewhat longer. Or make sure there is a carrier. The intent of the 
original 1 second delay was to let the link come up!

Micha
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