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SubjectRe: 2.5.40: problem with configuration system
On Sun, 6 Oct 2002 16:28:09 -0500 (CDT), Thomas Molina wrote:
>I was configuring a kernel for a rescue disk, so lots of things were not
>configured that normally would be. At the end of the compile I get:
>arch/i386/kernel/built-in.o: In function `MP_processor_info':
>arch/i386/kernel/built-in.o(.text.init+0x31ab): undefined reference to
>The thing I don't understand is why they should be set to y. My
>understanding from reading the source is that they should only be y if
>CONFIG_X86_LOCAL_APIC is y. That should only happen if CONFIG_SMP is not
>y and CONFIG_X86_UP_APIC is y. The enclosed .config file shows this isn't
>the case. What am I missing?

This happened to me recently when I copied a .config which had
UP_APIC=y and used make config to disable UP_APIC. The problem in
my case was that the good ole' Configure script doesn't always
reach a fixpoint in one iteration: the fact that LOCAL_APIC=y at the
start is sufficient for it to emit MPPARSE=y at the end, even though
LOCAL_APIC got disabled. A 'make oldconfig' should fix the situation.

This is not the only case where Configure gets it wrong. There is
a bug involving dep_tristate, forward dependencies, and toggling
module support which I reported to LKML ages ago (with a fix), but
nobody cared so... FWIW, the fix to that bug is included below.


--- linux-2.5.40/scripts/Configure.~1~ Thu Oct 3 00:00:00 2002
+++ linux-2.5.40/scripts/Configure Thu Oct 3 18:32:20 2002
@@ -316,7 +316,13 @@
- need_module=1
+ # Note: "m" means "module" only when CONFIG_MODULES=y,
+ # otherwise it really means "y". This matters when
+ # a dep_tristate dependency is a forward reference
+ # which we haven't yet "corrected" from "m" to "y".
+ if [ "$CONFIG_MODULES" = "y" ]; then
+ need_module=1
+ fi
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