Realtek Ethernet not working after kernel update

Question

After updating the CentOS 7.7 kernel from 3.10.0-957.27.2 to 3.10.0-1062.9.1, the Ethernet stopped working. The LEDs on the Ethernet port wouldn't light up and any attempt to ping anything resulted in a "host not reachable".

Everything looked ok with the files in /etc/sysconfig/network-scripts, and the output in /var/log/messages seemed to indicate that the interface was coming up correctly. Finally I booted the older 3.10.0-957.27.2 kernel and the Ethernet port immediately began working again.

When I run lspci -nnk it lists the Ethernet controller as:

07:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 03)
    Subsystem: Realtek Semiconductor Co., Ltd. RTL8111/8168 PCI Express Gigabit Ethernet controller [10ec:8168]
    Kernel driver in use: r8169
    Kernel modules: r8169

The output from lspci is identical under both kernels, including the "r8169" driver in use.

It looks like the Realtek drivers are included with the kernel because I see a lot of Realtek files under directories like:

/usr/lib/modules/3.10.0-1062.9.1.el7.x86_64/kernel/drivers/net/ethernet/realtek

But I see that although the Realtek driver filenames are the same, the sizes and dates have been updated for the newer kernel.

What's the best way to get the Ethernet controller working with the latest kernel?

Answer 1

I found an easy solution thanks to Anonymous who commented above with a link to a CentOS bug report. Apparently this is a known issue in the 1062 kernel and the driver is somehow not being loaded in the right order.

A quick fix to immediately activate the Ethernet port is to unload the r8169 driver and then reload it, but this doesn't survive a reboot:

# rmmod r8169
# modprobe r8169

You can skip that entirely though and fix the whole problem with one line that loads the Realtek module at the correct time using a config file. I can confirm that this does survive multiple reboots:

# echo realtek > /etc/modules-load.d/realtek.conf
(then reboot)

One thing that's curious is that when I booted from the old 957 kernel and did an lsmod I found that the realtek module wasn't being loaded then either, even though the Ethernet port worked fine. And the r8169 module was being loaded by both the old 957 kernel and the new 1062 kernel. But anyway, something's not being loaded in the right order by the 1062 kernel and this fixes it, so I'm all good now. Thanks again to Anonymous!

Answer 2

The only solution that I came across is this:

cat <<EOF| sudo tee /etc/systemd/system/load-realtek-driver.service
[Unit]
Description=Load Realtek drivers.
Before=network-online.target
    
[Service]
Type=simple
ExecStartPre=/usr/sbin/rmmod r8169
ExecStart=/usr/sbin/modprobe r8169
  
[Install]
WantedBy=multi-user.target
EOF
    
sudo systemctl enable load-realtek-driver.service

Or your an also just open up the service file like this using Nano or any other text editor:

sudo nano /etc/systemd/system/load-realtek-driver.service

And then adding this to that file:

[Unit]
Description=Load Realtek drivers.
Before=network-online.target

[Service]
Type=simple
ExecStartPre=/usr/sbin/rmmod r8169
ExecStart=/usr/sbin/modprobe r8169

[Install]
WantedBy=multi-user.target

Then start the service like this:

sudo systemctl start load-realtek-driver.service

And enable it so it can start on reboot like this:

sudo systemctl enable load-realtek-driver.service

Hope that helps someone!

Answer 3

also use crontab -e add this command

@reboot sleep 20  && /usr/sbin/rmmod  r8169 && /usr/sbin/modprobe r8169