Configuration language issues (was Re: drivers/net/Config.in cleanup)

• Next message: Jamie Lokier: "Re: Does your change make find faster by changing where it is storedor where it is returned?"
• Previous message: Mitchell Blank Jr: "[PATCH] missing permission checks for net_device.do_ioctl"
• In reply to: Tim Coleman: "Re: drivers/net/Config.in cleanup"
• Next in thread: Michael Elizabeth Chastain: "Re: Configuration language issues (was Re: drivers/net/Config.in cleanup)"
• Maybe reply: Michael Elizabeth Chastain: "Re: Configuration language issues (was Re: drivers/net/Config.in cleanup)"
• Maybe reply: Werner Almesberger: "Re: Configuration language issues (was Re: drivers/net/Config.in cleanup)"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

[ 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/

• Next message: Jamie Lokier: "Re: Does your change make find faster by changing where it is storedor where it is returned?"
• Previous message: Mitchell Blank Jr: "[PATCH] missing permission checks for net_device.do_ioctl"
• In reply to: Tim Coleman: "Re: drivers/net/Config.in cleanup"
• Next in thread: Michael Elizabeth Chastain: "Re: Configuration language issues (was Re: drivers/net/Config.in cleanup)"
• Maybe reply: Michael Elizabeth Chastain: "Re: Configuration language issues (was Re: drivers/net/Config.in cleanup)"
• Maybe reply: Werner Almesberger: "Re: Configuration language issues (was Re: drivers/net/Config.in cleanup)"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This archive was generated by hypermail 2b29 : Tue Mar 07 2000 - 21:00:23 EST