[Nix-dev] Debugging NixOS login problems

[Eelco Dolstra]

Hi,

On 05/06/2011 01:32 PM, Rickard Nilsson wrote:

> I have a sort-of working NixOS installation booting from an NFS root
> with only minor manual interventions. I pass init stage 1 and 2 just
> fine, and then get a login prompt. Now if I try to login with root or
> any other user, absolutely nothing happens. The login process just
> hangs, and nothing happens if I press Ctrl-C. I can switch to another
> tty and try to login there too, but nothing happens there either.

Probably the system locked up because the dhclient Upstart job brought 
down the network interface used to access the NFS disk.  Since the code 
to subsequently bring the interface up again resides on NFS, it hangs. 
I've had this problem in our VM tests (where we boot from a remote Nix 
store mounted via SMB).  It uses this workaround (from 
modules/virtualisation/qemu-vm.nix):

   # Starting DHCP brings down eth0, which kills the connection to the
   # host filesystem and thus deadlocks the system.
   networking.useDHCP = false;

-- 
Eelco Dolstra | http://www.st.ewi.tudelft.nl/~dolstra/