em0 doesn't work after upgrading from 11.0 to 11.1

[Frank Leonhardt]

On 2018-01-21 19:06, Khitai Pang wrote:
> I tried 11.1 amd64 iso installation in the same guest, and em0 didn't
> work.  I tried 10.4 amd64 iso installation in the guest and em0 dhcp
> worked fine.  So it appears that em0 driver of 11.1 is buggy?
> 
> How to rescue my kvm guest which has already upgraded to 11.1?
> 
> Regards
> Khitai
> ________________________________
> 寄件者: owner-freebsd-questions at freebsd.org
> <owner-freebsd-questions at freebsd.org> 代表 Khitai Pang
> <khitai.pang at outlook.com>
> 寄件日期: 2018年1月22日 上午 02:26:00
> 收件者: freebsd-questions at freebsd.org
> 主旨: em0 doesn't work after upgrading from 11.0 to 11.1
> 
> Hi,
> 
> 
> After the first reboot after upgrading my freebsd (in a kvm guest
> hosted on CentOS 6) from 11.0 to 11.1, em0 couldn't get IP address
> from DHCP:
> 
> 
> em0: Watchdog timeout -- resetting
> 
> em0: link state changed to DOWN
> 
> em0: link state changed to UP
> 
> 
> The above messages are repeated in dmesg.
> 
> 
> I reran "freebsd-update install" to complete the upgrade and rebooted
> the host again,  and the issue was still there.
> 
> 
> Networking worked perfectly fine before the upgrade.  /etc/rc.conf:
> 
> 
> hostname="..."
> 
> ifconfig_em0="DHCP"
> 
> sshd_enable="YES"
> 
> dumpdev="AUTO"
> 
> 
> Any idea?


The obvious answer is that KVM doesn't emulate the Intel NIC like the 
new driver expects. I prefer to run FreeBSD on real hardware, not a 
Linux emulation, so I'm guessing here.

Can you try defining a different NIC in the hypervisor and see of that 
works instead? I'd try a simple one like Realtek.

If that doesn't work and you have console access, try rebuilding the 
kernel with the Intel driver disabled and then copy the working 
/boot/kernel/if_em.ko across from the working platform and use 
loader.conf to bring it in. IME the chances are good it'll work with the 
new kernel.

Regards, Frank.