[ Added Cc to Michael Chastain ]
Tim Coleman wrote:
> As well, I wasn't aware that you could not define the same CONFIG_
> option twice. I have now been told as much. :)
This strikes me as a remarkable omission in
Documentation/kbuild/config-language.txt: it doesn't say much about
evaluation order (e.g. what happens when conflicting verbs meet, in
particular "unset" vs. anything else) or uniqueness requirements (e.g.
using multiple "define_bool"s is okay, while using multiple "bool"s
isn't).
Michael, could this omission be intentional ? :)
Evaluation order is a bit of a problem right now: xconfig and
menuconfig allow options to be probed before their definition, e.g.
you could (just as an example) show CONFIG_KMOD only if CONFIG_SCSI
is set. It works disturbingly well. As expected, make config
silently treats such options as "n". I didn't try mconfig, but I
guess it probably detects all this and complains.
USB configuration looks like a candidate for the first misguided
attempt to use the non-sequential evaluation offered by xconfig and
menuconfig, because some USB devices depend on components configured
"below" USB, e.g. V4L.
Considering the sequential nature of make (old)config , it seems
unlikely to me that anything other than strictly sequential
evaluation will be the norm anytime soon. This makes me wonder why
"unset" is considered a hack for a language problem in
config-language.txt (or did I mis-understand the comment there ?)
BTW, I think getting all configuration inter-dependencies properly
expressed in the various config.in files is a very worthwhile goal.
- Werner
-- _________________________________________________________________________ / Werner Almesberger, ICA, EPFL, CH werner.almesberger@ica.epfl.ch / /_IN_N_032__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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