NFSROOT and lagg(4)

[Jan Bramkamp]

On 04/02/2017 22:00, Konstantin Belousov wrote:
> On Sat, Feb 04, 2017 at 01:44:21PM -0700, Sean Bruno wrote:
>> "what I want" is to pxe/netboot and then switch over to using a lagg(4)
>> interface that includes the interface used in the pxe/netboot boot up.
>> I suspect, I have to switch to MDROOT to do this, but I thought I'd ask
>> if anyone is doing this type of configuration in their labs?
>>
>> What seems to happen is that I lose the nfsroot when I reconfigure the
>> lagg, and I no longer have access to reconfigure.
>>
>> e.g. pxeboot from em0, then reconfigure networking to use em0/em1 in lagg0:
>>
>> em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>>
>> options=5259b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,LRO,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO>
>>         ether 00:30:18:c5:0a:a9
>>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>>         media: Ethernet autoselect (1000baseT <full-duplex>)
>>         status: active
>> em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>>
>> options=5259b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,LRO,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO>
>>         ether 00:30:18:c5:0a:a9
>>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>>         media: Ethernet autoselect (1000baseT <full-duplex>)
>>         status: active
>> lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>>
>> options=5259b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,LRO,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO>
>>         ether 00:30:18:c5:0a:a9
>>         inet 192.168.100.53 netmask 0xffffff00 broadcast 192.168.100.255
>>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>>         media: Ethernet autoselect
>>         status: active
>>         groups: lagg
>>         laggproto lacp lagghash l2,l3,l4
>>         laggport: em0 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
>>         laggport: em1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
>>
>
> Look at reroot support, see reboot(8) option -r. I suspect you could
> need two reroots: first to some tmpfs or memory backed md(4) where
> ifconfig is present to reconfigure interfaces, second to boot into the
> final root.

You can't reroot into a tmpfs. It gets unmounted during the reroot which 
deletes every it ever contained.