[ Read through the thread, looked at Kconfig files,
did some tests. Adding Kconfig experts to Cc: list. ]
> On Thu, 2 Aug 2007, Sam Ravnborg wrote:
>
> > > >
> > > > ...
> > > > endif # NETDEVICES
> > > >
> > > > config NETPOLL
> > > > depends on NETDEVICES
> > > > def_bool NETCONSOLE
> > > >
> > > > config NETPOLL_TRAP
> > > > bool "Netpoll traffic trapping"
> > > > default n
> > > > depends on NETPOLL
> > > >
> > > > config NET_POLL_CONTROLLER
> > > > def_bool NETPOLL
> > > > depends on NETPOLL
Gargh, what we're seeing here is a whole bunch of bugs, I think. First
I thought this must be one of those randconfig-producing-wrong-configs
issues, but surprisingly, running "make oldconfig" on this .config on
a fresh 2.6.23-rc1-mm1 tree didn't change anything in the .config.
Kconfig bug #1:
===============
Which means, although:
*****
menuconfig BAZ
if BAZ
config BAR
endif
*****
is widely believed (by most folks, I've heard this on several threads,
and as written in the comment in drivers/net/Kconfig) to be equivalent to:
*****
menuconfig BAZ
if BAZ
endif
config BAR
depends on BAZ
*****
this is *not* enforced by "make oldconfig"! And hence, the NETPOLL &&
!NETDEVICES situation we're seeing here.
[ We could also categorize this as a bug in Kconfig's "if", fwiw. ]
Kconfig bug #2:
===============
config FOO
def_bool BAR
is supposed to ensure that FOO == BAR (as Matt mentioned earlier).
However, even this is *not* enforced by "make oldconfig". And hence,
the NETPOLL && !NET_POLL_CONTROLLER situation we're seeing here.
In fact, I believe it's possible to even pass a NETCONSOLE but
!NETPOLL kind of .config through "make oldconfig" but it still won't
catch it, and build breakages *will* occur.
[ We could also categorize this as a bug in Kconfig's "def_bool", fwiw. ]
Possibly, we could also decide to just blame "randconfig" for the whole
issue, and forget about these, because I think it's highly unlikely
(though not impossible) for people with "real" .configs to hit the
problems we saw above.
KGDBOE bug #1:
==============
config KGDBOE in lib/Kconfig.kgdb must also "depend on" NETDEVICES,
and select NET_POLL_CONTROLLER also.
KGDBOE bug #2:
==============
config KGDBOE_NOMODULE is a sad, sad option, and must be killed. The
"if !KGDBOE_NOMODULE" in KGDBOE must be removed, and it must lose its
dependency on "m".
Satyam
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