How do GEOM_PART_* options configure geom_part_* modules??

[Warner Losh]

On Thu, Sep 28, 2017 at 10:00 AM, Nick Hibma <nick at van-laarhoven.org> wrote:

> I created a new kernel config file from scratch, wondered what the
> GEOM_PART_MBR option and friends were doing, search for them, didn't find
> them in the tree, and deleted them from my config. But... de resulting disk
> image didn't boot, because of the fact that it didn't recognise the MBR
> partitions (it only had a single diskid entry on the mount-root prompt).
>
> Can anyone explain to me how these kernel options work, as in: they are
> defined in kernel configs and as a consequence in opt_geom.h, but how are
> they actually used to select which geom_part_* modules/kernel parts to
> build? I thought these options were translated to stuff that cpp would use,
> but there are not uses of for example GEOM_PART_MBR anywhere for example!
>
>
> The module always build them because they are listed in the module's
> Makefile.
>
> The kernel only sometimes does. Here's the key lines from conf/files:
> files:geom/geom_bsd_enc.c optional geom_bsd | geom_part_bsd
> files:geom/part/g_part_apm.c optional geom_part_apm
> files:geom/part/g_part_bsd.c optional geom_part_bsd
> files:geom/part/g_part_bsd64.c optional geom_part_bsd64
> files:geom/part/g_part_ebr.c optional geom_part_ebr
> files:geom/part/g_part_gpt.c optional geom_part_gpt
> files:geom/part/g_part_ldm.c optional geom_part_ldm
> files:geom/part/g_part_mbr.c optional geom_part_mbr
> files:geom/part/g_part_vtoc8.c optional geom_part_vtoc8
>
> which turn on/off which files get included. config "helpfully" converts the
> upper case options to lower case for this.
>
> Warner
>
>
> *slaps forehead* Goose chase!
>
> I actually knew that... and, at the time, thought it was weird behaviour.
> ''grep" would not have failed me if those options would be uppercase there
> ...
>

I've been nibbled to death by these geese often enough to have a PTSD-like
reaction when someone mentions it and habitually add -i to my greps...

Warner