dhclient SYNCDHCP messiness
Warren Block
wblock at wonkity.com
Wed Feb 22 21:09:00 UTC 2012
On Wed, 22 Feb 2012, Ian Lepore wrote:
> On Wed, 2012-02-22 at 11:40 -0700, Warren Block wrote:
>> In /etc/rc.conf:
>>
>> ifconfig_em0="SYNCDHCP"
>>
>> dhclient runs on startup, then later tries to run again:
>>
>> Starting dhclient.
>> em0: no link ...
>> .
>> .
>> got link
>> (...)
>> Starting Network: lo0 em0.
>> (...)
>> Starting devd.
>> Starting ums0 moused
>> .
>> dhclient already running? (pid=344).
>> Creating and/or trimming log files
>>
>> So is this from /etc/network.subr starting dhclient because the
>> interface is set to DHCP, then /etc/rc.d/dhclient running directly
>> later?
>>
>> This is with
>>
>> FreeBSD lightning 8.3-PRERELEASE FreeBSD 8.3-PRERELEASE #0: Tue Feb 21 22:25:30 MST 2012
>> root at lightning:/usr/obj/usr/src/sys/LIGHTNING i386
>
> From the sequence of things there it looks like the second invocation
> may be from a devd rule, but I thought all the standard rules used
> "dhclient quietstart" and that one of the effects of that was to supress
> the "already running" warning.
The devd rule triggers on a link up event. This is an em(4) card that
does not do the multiple up/down events on start like an re(4) card.
But easy to test. ...And interestingly enough, commenting out lines
51-56 of devd.conf stops the double call:
DHCPREQUEST on em0 to 255.255.255.255 port 67
DHCPACK from 10.0.0.1
bound to 10.0.0.8 -- renewal in 300 seconds.
Starting Network: lo0 em0.
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3<RXCSUM,TXCSUM>
inet 127.0.0.1 netmask 0xff000000
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9216
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:02:b3:a9:93:d7
inet 10.0.0.8 netmask 0xffffff00 broadcast 10.0.0.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
Starting devd.
Starting ums0 moused
.
Creating and/or trimming log files
For completeness, there's an unconnected re(4) card built into the
motherboard that shows "re0: link state changed to DOWN" immediately
after the "Starting devd." message.
AFAIK, it should happen like this:
ifconfig em0
em0 changes to up
dhclient em0 (sync)
wait until em0 gets a DHCP lease or fails
devd (em0 is already up, devd should do nothing)
So I guess the question is: why is devd seeing a link up event there?
> I updated a couple systems to 8.3-{PRERELEASE,BETA1} over the past few
> days and I haven't seen such a glitch. I don't think it should make a
> difference, but I use synchronous_dhclient=YES and ifconfig_foo=DHCP
That's a good point: testing... nope, it does the same thing as
"SYNCDHCP".
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