Re: building 9.1 kernel with /usr/src elsewhere?

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

> Date: Wed, 8 Mar 2023 08:58:47 -0500 (EST)
> From: Mouse <mouse%Rodents-Montreal.ORG@localhost>
> 
> Ugh, I hate using build.sh for small things like individual kernels.
> It always (well, far too often, at least) insists on rebuilding make,
> which takes significant time on some machines, like my shark, and
> requires extra writable filesystem space.  If there's a reasonably easy
> way to avoid it, I prefer to.

You could just cross-build on a modern machine for your shark...

> I don't squawk much about build.sh because it does bring benefits; the
> biggest one I notice is probably painless cross-compiles.  But I'd
> never run into this price before.  5.2 doesn't exhibit the misbehaviour
> at all, so I couldn't've noticed it except at work, and I think I've
> never tried to build a kernel without /usr/src in place before (at work
> or not).
> [...]
> > The problem is that NETBSDSRCDIR cannot be inferred for a randomly
> > located kernel builddir and sys/lib/libkern/Makefile.compiler-rt uses
> > it.
> 
> In that case, maybe config(1) should write a suitable setting of
> NETBSDSRCDIR into the Makefile it generates?  At least when -s is given
> with an absolute path?

It does put `S=/path/to/src/sys' into the kernel makefile, and _most_
of the kernel makefiles are written to use paths relative to $S, but
it looks like some ${NETBSDSRCDIR} has crept in between 5.2 and 9.1.

It probably wouldn't be wrong to make them use $S instead of
${NETBSDSRCDIR}, but you might be the first person to be affected by
this in years.