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

[Michael Ross]

Am 29.05.2012, 12:10 Uhr, schrieb Thomas Mueller <mueller23 at insightbb.com>:

> 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.
>
>

I often use nullfs for this kind of thing:

	mount -t nullfs /where/your/sources/are /usr/src
	mount -t nullfs /some/dir/for/objects /usr/obj


Michael