joi 2 septembrie 2021

Eddy Petrişor

Stretch to Buster upgrade issues: "Grub error: symbol ‘grub_is_lockdown’ not found", missing RTL8111/8168/8411 Ethernet driver and RTL8821CE Wireless adapter on Linux Kernel 5.10 (and 4.19)

joi 2 septembrie 2021, 19:30

I have been Debian Stretch running on my HP Pavilion 14-ce0000nq laptop since buying it back in April 2019, just before my presence at Oxidizeconf where I presented "How to Rust When Standards Are Defined in C".

Debian Buster (aka Debian 10) was released about 4 months later and I've been postponing the upgrade as my free time isn't what it used to be. I also tend to wait for the first or even second update of the release to avoid any sharp edges.

As this laptop has a Realtek 8821CE wireless card that wasn't officially supported in the Linux kernel, I had to use an out-of-tree hacked driver to have the wireless work on Stretch kernels such as 4.19, it didn't even got along with DKMS, so all compilations and installations of it, I did them manually. More reason to wait for a newer release that would contain a driver inside the official kernel.

I was waiting for the inevitable and dreading the wireless issues, but since mid-august Bullseye became stable, turning Stretch into oldoldstable, I decided that I had to do the upgrade, at least to buster.

The Grub error and the fix

Everything went quite smooth, except that after the reboot, the laptop failed to boot with this Grub error:

error: symbol ‘grub_is_lockdown’ not found

I looked for a solution and it seemed everyone was stuck or the solution was unclear.

There is even a bug report in Debian about this error, bug #984760.

Adding to the pile of confusion my own confused solution: I tried supergrubdisk2/rescatux, it didn't work for me, it might have been a combination of me using LVM and grub-efi-amd64. I also tried to boot in rescue mode the Buster first DVD (to avoid the need for network), I was able to enter the partition, mount the EFI partition, too, but since I didn't want to mess the setup even more or depend on an external USB stick, I didn't know where should I try to write the Grub EFI config - the root partition is on an NVME storage.

When buying the laptop it had FreeDOS installed on it and some HP rescue app, which I did not wipe when installing Debian. I even forgot where or how was the EFI installed on the disk and EFI, even if it should be more reliable and simpler, I never got the hang of it.

In the end, I realized that I could via BIOS actually select manually which EFI executable should be booted into, so I was able to boot with some manual intervention during boot into the regular system.

I tried regenerating the grub configuration, installing it and also tried restoring the default proper boot sequence (and I even installed refind in the system during my fumbling), but I think somewhere between grub-efi-amd64 reconfiguration and its reinstallation I managed to do the right thing, as the default boot screen is the Grub one now.

Hints for anyone reading this in the hope to fix the same issue, hopefully it will make things better, not worse (see the text below):

1) regenerate the grub config:

update-grub2
2) reinstall grub-efi-amd64 and make Debian the default

dpkg-reconfigure -plow grub-efi-amd64

When reinstalling grub-efi-amd64 onto the disk, I think the scariest questions were to these:

Force extra installation to the EFI removable media path?

Some EFI-based systems are buggy and do not handle new bootloaders correctly. If you force an extra installation of GRUB to the EFI removable media path, this should ensure that this system will boot Debian correctly despite such a problem. However, it may remove the ability to boot any other operating systems that also depend on this path. If so, you will need to make sure that GRUB is configured successfully to be able to boot any other OS installations correctly.

 and

Update NVRAM variables to automatically boot into Debian?

GRUB can configure your platform's NVRAM variables so that it boots into Debian automatically when powered on. However, you may prefer to disable this behavior and avoid changes to your boot configuration. For example, if your NVRAM variables have been set up such that your system contacts a PXE server on every boot, this would preserve that behavior.

I think the first can be safely answered "No" if you don't plan on booting via a removable USB stick, while the second is the one that does the restoring.

The second question is probably safe if you don't use PXE boot or other boot method, at least that's what I understand. But if you do, I suspect by installing refind, by playing with the multiple efi* named packages and tools, you can restore that, or it might be that your BIOS allows that directly.

I just did a walk through of these 2 steps again on my laptop and answered "No" to the removable media question as it leads to errors when the media was not inserted (in my case the internal SD card reader), and "Yes" to making Debian the default.

It seems that for me this broke the FreeDOS and HP utilities boot entries from Grub, but I still can boot via the BIOS options and my goal was to have Debian boot correctly by default.

Fixing the missing RTL811/8168/8411 Ethernet card issue

As a side note for people with computers having Realtek RTL8111/8168/8411 Gigabit Ethernet Controller and upgrading to Buster or switching to a newer kernel, please note that you might end up having the unpleasant surprise even your Ethernet card to disappear because the r8169 driver is not loader by default.

I had to add it to /etc/modules so is loaded by default:

eddy@aptonia:/ $ cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
r8169

The 5.10 compatible driver for RTL8821CE wireless adapter

After the upgrade to Buster, the oldstable version of the kernel, 4.19, the hacked version of the driver I've been using on Stretch on 4.9 kernels was no longer compatible - failed to compile due to missing symbols.

The fix for me was to switch to the DKMS compatible driver from https://github.com/tomaspinho/rtl8821ce, as this seems to work for both 4.19 and 5.10 kernels (installed from backports).

I installed it via a modification of the manual install method only for the 4.19 and 5.10 kernels, leaving the legacy 4.9 kernels working with the hacked driver. You can do the same if instead of running the provided script, you do its steps manually and you install only for the kernel versions you want, instead of the default to install for all:

I looked inside the dkms-install.sh script to do the required steps:

Copy the driver, add it to the dkms set of known drivers:

DRV_NAME=rtl8821ce
DRV_VERSION=v5.5.2_34066.20200325

cp -r . /usr/src/${DRV_NAME}-${DRV_VERSION}

dkms add -m ${DRV_NAME} -v ${DRV_VERSION}

But you just build and install them only for the select kernel versions of your choice:

dkms build -m ${DRV_NAME} -v ${DRV_VERSION} -k 5.10.0-0.bpo.8-amd64
dkms install -m ${DRV_NAME} -v ${DRV_VERSION} -k 5.10.0-0.bpo.8-amd64

 Or, without the variables:

dkms build rtl8821ce/v5.5.2_34066.20200325 -k 4.19.0-17-amd64
dkms install rtl8821ce/v5.5.2_34066.20200325 -k 4.19.0-17-amd64

dkms status should confirm everything is in place and I think you need to update grub2 again after this.

Please note this driver is no longer maintained and the 5.10 tree should support the RTL8821CE wireless card with the rtw88 driver from the kernel, but for me it did not. I'll probably try this at a later time, or after I upgrade to the current Debian stable, Bullseye.

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