https://boinc.berkeley.edu/wiki/Installing_BOINC_on_Gentoo et seq tell us to run BOINC as a daemon. That's fine for projects that don't use VirtualBox, but those that do use it cannot communicate with it when run as a daemon.

The Gentoo package sci-apps/boinc has a start/stop script which calls boinc as a daemon, and that needs changing too. I've raised a bug at https://bugs.gentoo.org/show_bug.cgi?id=581652 to request a corresponding change in the script.

I don't think the problem is starting the client as a daemon rather then starting as the correct user. On Debian there is a user "boinc" that comes with the package and with which VirtualBox is available to the Client.

From your bug report at gentoo it is not clear to me if and how you solved the problem on your computer. From the wiki page you mentioned the Gentoo package also creates a "boinc" user. What you see is maybe a security feature on Gentoo where you need to allow the "boinc" user to manage VirtualBox. This would still mean that BOINC is run as a daemon but now has the correct access.

The way I solved the problem, after spending three weeks trying to find another way, was to uninstall the Gentoo package, then install the BOINC project version (both at 7.2.42). There was no difference - "Communication with VM hypervisor failed." So I changed the script /home/prh/boinc/run_manager to remove the --daemon flag and add an ampersand:

prh@peak ~/boinc $ cat run_manager
cd "/home/prh/BOINC" && exec ./boincmgr $@ &

Now it works fine (BOINC is a soft link to boinc, which is where I mount the partition devoted to BOINC).

I'll prove it conclusively by reverting to the Gentoo package and changing the init script to remove --daemon. I'd better also see if I can make my Gentoo bug report clearer.

I'm not aware of any special security feature of Gentoo other than the standard Linux permissions setup; I certainly don't have any security package installed. How has Debian solved the problem? What does its boinc init script look like?

I've added boinc and myself to vboxusers, and I've added myself to boinc and vboxusers. I've checked file and directory permissions and everything else I can think of. Running other than as a daemon is the only way I've found to work here.

Well, now I don't know what's going on. I have reinstalled sci-misc/boinc and I've found that the init script differs from what I backed up six hours ago. It now uses start-stop-daemon instead of su -m. No changelog entries, no version bump, just a different date on a couple of files.

It's too early to say whether this has worked as a whole lot of downloads are now in progress, as though all work done before has been lost. Watch this space...

Looks like you were right, Christian. The problem was not with running as a daemon but in being started with an su command. This has now been fixed in Gentoo by substituting a call to start-stop-daemon.

Sorry I mis-diagnosed this.

Please, do I need to add a warning to the install instructions that when running BOINC as a daemon, it cannot find VirtualBox, or not?
Is that also (still) the fact with Windows installations and BOINC as a service, or is it cleared there as well?

Thanks.

---

Here is the commit: https://gitweb.gentoo.org/repo/gentoo.git/commit/sci-misc/boinc?id=6fbb2367cc20a9b34acde2f1df699900f310a9cf

This was first reported here: https://github.com/gentoo/gentoo/pull/1244

Regards
Christian

Please, do I need to add a warning to the install instructions that when running BOINC as a daemon, it cannot find VirtualBox, or not?

No, I don't think any action is needed here. I was mistaken in my diagnosis. I'll see if I can find where moving away from su is recommended, and make a note there if suitable.

Is that also (still) the fact with Windows installations and BOINC as a service, or is it cleared there as well?

Sorry; I can't help with Windows hosts.