User manual

Linux
18
Host software requirements (Linux)
VAX MP requires Linux kernel version 2.6.38 or later. You can check the version of your system’s kernel
using command
uname -r.
VAX MP also requires version of GLIBC with NPTL threads. We recommend using GLIBC version 2.13 or
later. The way to check the version of GLIBC currently installed on the system depends on a flavor your
Linux distribution. One common way is to execute command
ldd --version. Another way is to locate
your GLIBC shared library and simply execute it as any executable file, for example as
bash$ /lib/libc.so.6
and to look for the information in produced output.
When executing VAX user-mode code, VAX MP virtual CPU threads run at low Linux priority
corresponding to
nice +10. However critical sections of OpenVMS are executed at elevated VCPU
thread priorities and VAX MP will use real-time priority range for its threads to execute OpenVMS critical
sections. Highest priority used by VAX MP is displayed at VAX MP startup; currently it is 37. It is
important that Linux account used to run VAX MP has proper permissions to elevate thread priority to
this value, otherwise VAX MP and guest OS (OpenVMS) may run poorly. If login account does not
provide adequate permissions for VAX MP to elevate its threads to required priority level, VAX MP will
display a warning message at startup.
Unless you use superuser/root account or
sudo command to execute VAX MP, the easiest way to allow
priority elevation for regular account is via file
/etc/security/limits.conf. Add the following lines to
limits.conf, where vaxuser is the username of the account used to run VAX MP:
vaxuser hard nice -20
vaxuser soft nice -10
vaxuser hard rtprio 37
vaxuser soft rtprio 10
The changes to
/etc/security/limits.conf become effective after login, so if you performed them
while logged into
vaxuser account, then you need to log off and log on back again.
Alternatively, you can grant the account capability CAP_SYS_NICE and use Linux command
chrt to
launch VAX MP.
Host networking software configuration (Linux)
Use of VAX MP networking features requires the latest version of
libpcap package be installed. At the
time of writing, this is package
libpcap0.8 with actual version 1.1.1-2; you can check for latest
available version with tools like Synaptic Package Manager or equivalent. For example:
sudo apt-get install libpcap0.8