[vbox-dev] Cannot compile VirtualBox 5.1.30 without access to kernel sources (regression since 5.1.12)

[Ulrich Gemkow]

Hello,

VirtualBox 5.1.30 can no longer be compiled when the kernel sources
are not available during the build. The compile fails with the error

-- kBuild: Installing /lnc/build/apps/make/VirtualBox-5.1.30/out/linux.amd64/release/misc-staging/rdesktop-1.8.3-vrdp/include/iprt/linux/sysfs.h
kBuild: Installing /lnc/build/apps/make/VirtualBox-5.1.30/out/linux.amd64/release/misc-staging/rdesktop-1.8.3-vrdp/include/iprt/list.h
/lnc/build/apps/make/VirtualBox-5.1.30/out/linux.amd64/release/obj/tstguest_mod/vboxguest/Makefile.include.header:112: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again.  Stop.
make[1]: Leaving directory '/lnc/build/apps/make/VirtualBox-5.1.30/out/linux.amd64/release/obj/tstguest_mod/vboxguest'
kBuild: Installing /lnc/build/apps/make/VirtualBox-5.1.30/out/linux.amd64/release/misc-staging/rdesktop-1.8.3-vrdp/include/iprt/lockvalidator.h
Makefile:30: recipe for target 'all' failed

configure is called with the following parameters:

./configure --disable-kmods --disable-pulse --disable-alsa --disable-hardening --disable-opengl --disable-dbus --disable-docs --disable-python --disable-java --disable-libvpx

The compile host is a modified Ubuntu 16.04 with a vanilla kernel
Linux 4.9.

The error did not happen when compiling 5.1.12 in exact the
same configuration, so this is a regression.

IMHO it should be possible to compile VirtualBox without access
to the kernel sources when --disable-kmods is given - not only
for security reasons.

Thanks and best regards

Ulrich

-- 
Ulrich Gemkow
University of Stuttgart, Germany
Institute of Communication Networks and Computer Engineering (IKR)