Enabling vsyscall on Debian

Introduction

If you are using one of the latest Debian versions, you may need to enable vsyscall which is disabled by default for some kernel versions, for example, for Debian 9 (Stretch) with kernel 4.18.x.bpo and Debian 10 (Buster) RC1 with kernel 4.19.0.

vsyscall is a mechanism that is used to accelerate certain system calls on Linux. It is required for the ONLYOFFICE Mail to work correctly. To be able to run the ONLYOFFICE Mail Docker container and to ensure the ONLYOFFICE Mail correct work, please follow the instructions below.

Checking if vsyscall is disabled

To check if your system has disabled vsyscall execute the following command:

cat /proc/self/maps | egrep 'vdso|vsyscall'

You'll see output similar to the following:

7fffccfcc000-7fffccfce000 r-xp 00000000 00:00 0                          [vdso]

or you'll see output like this:

7fffe03fe000-7fffe0400000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

If you do not see a vsyscall mapping, add the vsyscall=emulated to the kernel options in your bootloader, as it is described in the next step.

Enabling vsyscall

To enable vsyscall on your operating system, execute the following commands:

echo 'GRUB_CMDLINE_LINUX_DEFAULT="vsyscall=emulate"' >> /etc/default/grub

This command specifies the parameter that allows to load kernel with vsyscall enabled on the system boot and adds this parameter to the /etc/default/grub file that contains main settings for the GRUB bootloader.

After the /etc/default/grub file is changed, you need to update GRUB:

update-grub

Now reboot the system:

reboot

After the system is rebooted, you can proceed to the ONLYOFFICE Mail Docker version installation.