Hi,

If there are no other plans of kconfig docs update I think this
message of yours should be useful enough. I made minimal fixes,
so if they are wrong or you prefer it otherwise, I'm OK with any
change to this proposal, including replacement with something
else.

Thanks & regards,
Jarek P.

On Thu, Aug 02, 2007 at 11:36:59AM +0200, Sam Ravnborg wrote:
...

quoted

quoted

seems to select NET_POLL_CONTROLLER after selecting NETPOLL, but
still doesn't check for NETDEVICES dependency.

That's odd. Adding Sam to the cc:.

select is evil....
select will by brute force set a symbol equal to 'y' without
visiting the dependencies.
So abusing select you are able to select a symbol FOO even 
if FOO depends on BAR that is not set.

In general use select only for non-visible symbols (no promts anywhere)
and for symbols with no dependencies.
That will limit the suefullness but on the other hand avoid the illegal
configurations all over.

kconfig should one day warn about such things but I have not fel inclined
to dive into the matters hoping that Roman does one day.

	Sam

----------->

Subject: docs: a warning note about select in kconfig-language.txt

A warning note of Sam Ravnborg about kconfig's select evilness,
dependencies and the future (slightly corrected).

Signed-off-by: Jarek Poplawski <redacted>
Cc: Sam Ravnborg <redacted>

---

diff -Nu9r 2.6.23-rc1-/Documentation/kbuild/kconfig-language.txt 2.6.23-rc1/Documentation/kbuild/kconfig-language.txt

--- 2.6.23-rc1-/Documentation/kbuild/kconfig-language.txt	2007-07-09 01:32:17.000000000 +0200
+++ 2.6.23-rc1/Documentation/kbuild/kconfig-language.txt	2007-08-06 12:50:34.000000000 +0200

@@ -92,18 +92,27 @@
 
 - reverse dependencies: "select" <symbol> ["if" <expr>]
   While normal dependencies reduce the upper limit of a symbol (see
   below), reverse dependencies can be used to force a lower limit of
   another symbol. The value of the current menu symbol is used as the
   minimal value <symbol> can be set to. If <symbol> is selected multiple
   times, the limit is set to the largest selection.
   Reverse dependencies can only be used with boolean or tristate
   symbols.
+  Note:
+	select is evil.... select will by brute force set a symbol
+	equal to 'y' without visiting the dependencies. So abusing
+	select you are able to select a symbol FOO even if FOO depends
+	on BAR that is not set. In general use select only for
+	non-visible symbols (no promts anywhere) and for symbols with
+	no dependencies. That will limit the usefulness but on the
+	other hand avoid the illegal configurations all over. kconfig
+	should one day warn about such things.
 
 - numerical ranges: "range" <symbol> <symbol> ["if" <expr>]
   This allows to limit the range of possible input values for int
   and hex symbols. The user can only input a value which is larger than
   or equal to the first symbol and smaller than or equal to the second
   symbol.
 
 - help text: "help" or "---help---"
   This defines a help text. The end of the help text is determined by