Building "third-party" modules for kernel with debug options?

[John Baldwin]

On Friday, January 07, 2011 7:15:59 am Lev Serebryakov wrote:
> Hello, Freebsd-hackers.
> 
> 
>   I've found, that "struct bio" is depend on state of "DIAGNOSTIC"
> flag ("options DIAGNOSTIC" in kernel config). But when I build
> third-party GEOM (or any other) module with using of <bsd.kmod.mk>,
> there is no access to these options. So, module, built from ports, can
> fail on user's kernel, even if it built with proper kernel sources in
> "/usr/src/sys". Is here any solution for this problem?
> 
> P.S. NB: GEOM module is only example, question is about modules &
> kernel options in general, so I put this message on Hackers list.

In general we try to avoid having "public" kernel data structures change size 
when various kernel options are in use.  Some noticeable exceptions to this 
rule are PAE (i386-only) and LOCK_PROFILING (considered to be something users 
would not typically use).  DIAGNOSTIC might arguably be considered the same as 
LOCK_PROFILING, but I am surprised it affects bio.  It should only affect a 
GEOM module that uses bio_pblockno however in this case since you should be 
using kernel routines to allocate bio structures rather than malloc'ing one 
directly.  Perhaps phk@ would ok moving bio_pblockno up above the optional 
diagnostic fields.

-- 
John Baldwin