em(4) on FreeBSD is sometimes annoying

Jack Vogel jfvogel at gmail.com
Fri Aug 15 03:02:19 UTC 2008

I fought with this issue all day today, trying to root cause it, and while I
don't have a solution I do have a better understanding of it.

I was wrong about it being the interrupt handler, at least if there's any
issue with it its not the primary cause. I actually found out using a
Fedora Live CD that Linux seems to have the same issue, but its
symptoms are slightly different due to driver architecture differences.
If you boot Linux with no cable in, and then modprobe the e1000
driver you get no errors, however, when you follow that with an
'ifconfig eth0' it will fail saying that it cannot find the device!!

Do the same with the cable in and it all works.

The same 82573 NIC on a standalone adapter has NONE of these
problems, it all works fine.

So, right now my theory is the power system of the laptop is
putting the phy into a sleep state due to having no link and
neither our driver or the Linux driver has a way to bring it back
out of that state.

Until this gets worked out all I can tell you is "keep that cable
IN"  :)


On Thu, Aug 14, 2008 at 4:33 AM, Markus Vervier <markus at vervier.info> wrote:
> Hash: SHA1
> Jack Vogel wrote:
> | I have reproduced the problem, you are correct. Thank you for
> | persisting thru my doubts :)
> Always persisting to help improving FreeBSD. Another odd thing I noticed
> today:
> When dual-booting Windows on the same machine and doing a warm-reboot from
> Windows to FreeBSD,
> you _do_ get a link with the procedure I described yesterday.. So there
> seems to be some setting which is lost
> after cold-boot or some EEPROM setting which is changed somehow.
> | OH, I should note that as long as you put in a cable before you
> | ifconfig up its fine so
> | its not that hard to work around the issue.
> I completly forgot about the issue until now, after I noticed it some time
> ago when being overworked. :-(
> The situation just does not occur very often in times of wireless LAN /
> Docking Stations. :-)
> - --
> Markus
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> iiIAoNrPUTE0veViP7Zklm7jD25m7Aad
> =DrBs
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