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After the latest update to Ubuntu Studio 20.04.1, my desktop system can't access the Ethernet card (no LEDs light up) and I have no Internet connection. The latest installed kernel in my system is 5.4.0-56-lowlatency. I'm able to boot the system with the previous kernel, 5.4.0-54-lowlatency and then the Ethernet card works fine and I can connect. I've read that this bug might have been fixed in kernel 5.4.0.56.62, but I guess this isn't a lowlatency one.

  • How can I boot normally on the latest kernel and have Ethernet working?
  • How can I update my current kernel to the one that fixes the
    Ethernet bug?

Edit 1: I just updated the kernel to version 5.4.0-58-lowlatency but the problem persists.

Edit 2: This issue is present in kernels as recent as 5.8.0-33.36. See this bug for more info: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1906655

Thanks.

Edit: output of dpkg -l | grep linux below:

ii  binutils-x86-64-linux-gnu                     2.34-6ubuntu1                          amd64        GNU binary utilities, for x86-64-linux-gnu target
ii  console-setup-linux                           1.194ubuntu3                           all          Linux specific part of console-setup
ii  fonts-linuxlibertine                          5.3.0-4                                all          Linux Libertine family of fonts
ii  ladspa-sdk                                    1.15-2build1                           amd64        sample tools for linux-audio-dev plugin architecture
ii  liblinux-epoll-perl                           0.017-1                                amd64        perl epoll module for O(1) multiplexing
ii  libselinux1:amd64                             3.0-1build2                            amd64        SELinux runtime shared libraries
ii  libselinux1:i386                              3.0-1build2                            i386         SELinux runtime shared libraries
ii  libv4l-0:amd64                                1.18.0-2build1                         amd64        Collection of video4linux support libraries
ii  libv4lconvert0:amd64                          1.18.0-2build1                         amd64        Video4linux frame format conversion library
ii  linux-base                                    4.5ubuntu3.1                           all          Linux image base package
ii  linux-firmware                                1.187.4                                all          Firmware for Linux kernel drivers
ii  linux-headers-5.4.0-54                        5.4.0-54.60                            all          Header files related to Linux kernel version 5.4.0
ii  linux-headers-5.4.0-54-lowlatency             5.4.0-54.60                            amd64        Linux kernel headers for version 5.4.0 on 64 bit x86 SMP
ii  linux-headers-5.4.0-56                        5.4.0-56.62                            all          Header files related to Linux kernel version 5.4.0
ii  linux-headers-5.4.0-56-lowlatency             5.4.0-56.62                            amd64        Linux kernel headers for version 5.4.0 on 64 bit x86 SMP
ii  linux-headers-lowlatency                      5.4.0.56.59                            amd64        lowlatency Linux kernel headers
rc  linux-image-4.15.0-112-lowlatency             4.15.0-112.113                         amd64        Signed kernel image lowlatency
rc  linux-image-4.15.0-115-lowlatency             4.15.0-115.116                         amd64        Signed kernel image lowlatency
rc  linux-image-4.15.0-117-lowlatency             4.15.0-117.118                         amd64        Signed kernel image lowlatency
rc  linux-image-4.15.0-118-lowlatency             4.15.0-118.119                         amd64        Signed kernel image lowlatency
rc  linux-image-5.4.0-48-lowlatency               5.4.0-48.52                            amd64        Signed kernel image lowlatency
rc  linux-image-5.4.0-51-lowlatency               5.4.0-51.56                            amd64        Signed kernel image lowlatency
rc  linux-image-5.4.0-52-lowlatency               5.4.0-52.57                            amd64        Signed kernel image lowlatency
rc  linux-image-5.4.0-53-lowlatency               5.4.0-53.59                            amd64        Signed kernel image lowlatency
ii  linux-image-5.4.0-54-lowlatency               5.4.0-54.60                            amd64        Signed kernel image lowlatency
ii  linux-image-5.4.0-56-lowlatency               5.4.0-56.62                            amd64        Signed kernel image lowlatency
ii  linux-image-lowlatency                        5.4.0.56.59                            amd64        lowlatency Linux kernel image
ii  linux-libc-dev:amd64                          5.4.0-56.62                            amd64        Linux Kernel Headers for development
ii  linux-lowlatency                              5.4.0.56.59                            amd64        Complete lowlatency Linux kernel
rc  linux-modules-4.15.0-112-lowlatency           4.15.0-112.113                         amd64        Linux kernel extra modules for version 4.15.0 on 64 bit x86 SMP
rc  linux-modules-4.15.0-115-lowlatency           4.15.0-115.116                         amd64        Linux kernel extra modules for version 4.15.0 on 64 bit x86 SMP
rc  linux-modules-4.15.0-117-lowlatency           4.15.0-117.118                         amd64        Linux kernel extra modules for version 4.15.0 on 64 bit x86 SMP
rc  linux-modules-4.15.0-118-lowlatency           4.15.0-118.119                         amd64        Linux kernel extra modules for version 4.15.0 on 64 bit x86 SMP
rc  linux-modules-5.4.0-48-lowlatency             5.4.0-48.52                            amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
rc  linux-modules-5.4.0-51-lowlatency             5.4.0-51.56                            amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
rc  linux-modules-5.4.0-52-lowlatency             5.4.0-52.57                            amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
rc  linux-modules-5.4.0-53-lowlatency             5.4.0-53.59                            amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
ii  linux-modules-5.4.0-54-lowlatency             5.4.0-54.60                            amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
ii  linux-modules-5.4.0-56-lowlatency             5.4.0-56.62                            amd64        Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP
ii  linux-sound-base                              1.0.25+dfsg-0ubuntu5                   all          base package for ALSA and OSS sound systems
ii  pptp-linux                                    1.10.0-1build1                         amd64        Point-to-Point Tunneling Protocol (PPTP) Client
ii  util-linux                                    2.34-0.1ubuntu9.1                      amd64        miscellaneous system utilities
Jordi
  • 39
  • Check if linux-modules-extra- are installed for the last kernel. – Pilot6 Dec 03 '20 at 14:39
  • Thank you. They don't seem to be installed. I'm using apt show linux-modules-extra- and it doesn't find anything. apt list --installed | grep linux-modules-extra- also doesn't find anything. How can I install them without an Internet connection? Do you recommend a fresh install? – Jordi Dec 04 '20 at 17:08
  • Please add output of dpkg -l | grep linux to your question. – Pilot6 Dec 04 '20 at 17:16
  • Output added above. – Jordi Dec 04 '20 at 17:44
  • It looks good to me. But I don't have much experience with lowlatency kernels. – Pilot6 Dec 04 '20 at 21:28
  • Thanks for your help. I'm not knowledgeable enough to know exactly what's wrong. I think I'll just do a fresh install from the distribution image. – Jordi Dec 04 '20 at 22:34
  • Well this may be a kenel bug. First try to upgrade kernel. – Pilot6 Dec 05 '20 at 10:12
  • I'm not sure how to do that. Under the earlier kernel, update manager says the system is up to date and under the latest kernel I have no Internet connection. – Jordi Dec 05 '20 at 11:29
  • I can reproduce this issue on 5.4.0-58-generic as well. I hope there are solutions – mask8 Dec 12 '20 at 18:16
  • It seems that this bug is still present in kernels as recent as 5.8.0-33.36. See this bug report for more info: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1906655 – Jordi Dec 13 '20 at 00:07

4 Answers4

1

I found a solution. What it was missing was linux-modules-extra-5.4.0-58-?

I booted linux with the previous 5.4.0-54, then install the linux-modules-extra for the latest version for the kernel image, then reboot. It worked on my generic kernel image.

For some reason, when I ran apt upgraded, it did not install the extra package. I don't know why.

mask8
  • 111
  • Thank you. Unfortunately I'm using a lowlatency kernel, not a generic one, and there's no such linux-modules-extra-5.4.0-58-lowlatency package that corresponds to it. – Jordi Dec 13 '20 at 00:05
  • @Jordi I see. then probably try dkms package for your network driver. for instance my realtek card uses r8169 driver, so I can technically install r8168-dkms deb package without installing extra module package to support the card. this answer may help you https://askubuntu.com/questions/1241785/i-clean-installed-20-04-lts-but-now-i-have-no-network#1242028 – mask8 Dec 14 '20 at 03:00
  • Thank you. According to this bug report (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1906655), a fix for the network driver "r8169: fix issue with forced threading in combination with shared interrupts" will be released in kernel version 5.8.0-34.37. – Jordi Dec 14 '20 at 04:00
0

I'm facing the same issue: there is something not correctly working with the newest lowlatency kernel when using a Realtek network card, that is causing and irq mismatch between the ethernet card and other devices (in my case, the ahci: you can check it by using "dmesg | tail"); in my case:

[ 4.636432] genirq: Flags mismatch irq 19. 00010080 (enp2s0) vs. 00002080 (ahci[0000:00:1f.2])

I can use the network only by loading a non-lowlatency kernel: in order to do so, hold the shift button just after the initial BIOS screen: this way you'll enter the grub2 menu, choose "advanced options" and then select the kernel (not lowlatency) you want to use.

This way, I'm able to surf again. The drawbacks are that:

  • the procedure has to be done manually after each boot
  • the lowlatency kernel's features won't be available.

Hope they are going to fix this ASAP!

MarcoPippo
  • 1
  • Thanks. Yes, as I say in the question, that's what I've been doing for now, booting with a previous version of the kernel, which in my case is low latency as well. – Jordi Dec 06 '20 at 16:34
0

The recent kernel update to version 5.4.0-59 solved the problem. The Ethernet works correctly. Thanks for all the answers and comments.

Jordi
  • 39
-2

Have you got the proprietary drivers?

check if in your /etc/apt/sources.list there is this line

deb http:/YOURREPOSITORYADRESS YOURUBUTUVERSION main contrib non-free

or

deb http://YOURREPOSITORYADRESS/ubuntu/ YOURUBUNTUVERSION main restricted universe multiverse

after, give us the output of dmesg -l err

Luca Ravasio
  • 21
  • I don't have such line in /etc/apt/sources.list. I'm only using a proprietary driver for my Nvidia graphics card, but none for the network controller. The output of dmesg -l err is: [ 41.095297] genirq: Flags mismatch irq 16. 00010080 (enp4s0) vs. 00002080 (uhci_hcd:usb3). – Jordi Dec 12 '20 at 23:58
  • Try to boot with 5.4.0-54-lowlatency. I find the solution here --> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1906655 – Luca Ravasio Dec 13 '20 at 11:06
  • Have you got firmware-realtek package? – Luca Ravasio Dec 13 '20 at 11:08
  • Thank you. Yes, I'm booting with that previous version of kernel, I say that above right in the description. I don't have that package but I think that the problem is in the interrupt management in the kernel. According to this bug report (http://bugs.launchpad.net/ubuntu/+source/linux/+bug/1906655), a fix for the network driver "r8169: fix issue with forced threading in combination with shared interrupts" will be released in kernel version 5.8.0-34.37. – Jordi Dec 14 '20 at 04:04