How to indicate source directory in other than /usr/src?

[Thomas Mueller]

How does one indicate a system source directory location when in other than /usr/src?

That could be necessary when in another directory, for instance running ndiscvt.

Or one could be building FreeBSD for a USB stick and want to do the heavy work on a hard drive; I could also want to build and install ports on the USB stick but do the heavy work on the hard drive.

I couldn't find a variable named SRCDIR anywhere in the documentation, in contrast to PORTSDIR, which I did find.

I may also want to build 10-CURRENT from 9-STABLE system without giving up the 9-STABLE source tree; I would need both source trees, but then after the first successful build of 10-CURRENT, I could use that to build updated versions.


Tom