Re: [PATCH] CONFIG_TR/CONFIG_LLC: work around the problem with select

On Sun, 2012-02-05 at 06:31 +0000, Al Viro wrote:

As it is, with PCI/ISA/MCA/CCW all set to n and PCMCIA set to m
setting TR to y will set LLC to m, with very unpleasant results -
net/802/psnap gets picked into obj-y, resulting in the kernel
that won't link - psnap calls functions from llc.  The cause,
AFAICS, is that kconfig gets rev_dep for LLC containing
|| TR && (deps for TR)
and even though TR is boolean, both LLC and PCMCIA are tristate
and that thing becomes || y && (n || m), i.e. || m.  The reason
for dependency on PCMCIA is that when none of PCI, ISA, MCA, CCW
or PCMCIA is set there'll be no tokenring drivers, so there's no
point building tokenring core.  Proper fix probably belongs in
kconfig (we need strict and, such that y <strict_and> m would be
y, so that rev_deps added for tristate selected by bool would
use that instead of &&; we'd have || TR <strict_and> (deps for TR)
in this case), but it's a rather intrusive change.  There's an
easy workaround in case of TR -> LLC select, namely to have a def_bool y
symbol sitting under if TR and have that symbol selecting LLC.
Kudos to johill for suggesting that one...

[...]

This is pretty subtle; maybe it warrants a comment above WANT_LLC?

Ben.

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Ben Hutchings, Staff Engineer, Solarflare
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