On Thu, 14 Sep 2023, "Arnd Bergmann" <arnd@xxxxxxxx> wrote: > On Thu, Sep 14, 2023, at 15:42, Jani Nikula wrote: >> On Wed, 13 Sep 2023, Arnd Bergmann <arnd@xxxxxxxxxx> wrote: >>> From: Arnd Bergmann <arnd@xxxxxxxx> >>> >>> +Optional dependencies >>> +~~~~~~~~~~~~~~~~~~~~~ >>> + >>> +Some drivers are able to optionally use a feature from another module >>> +or build cleanly with that module disabled, but cause a link failure >>> +when trying to use that loadable module from a built-in driver. >>> + >>> +The most common way to express this optional dependency in Kconfig logic >>> +uses the slighly counterintuitive >>> + >>> + config FOO >>> + bool "Support for foo hardware" >>> + depends on BAR || !BAR >> >> depends on BAR || BAR=n >> >> seems to be an alternative that's about as common: >> >> $ git grep "depends on \([A-Z0-9_]\+\) || \!\1" | wc -l >> 109 >> $ git grep "depends on \([A-Z0-9_]\+\) || \1=n" | wc -l >> 107 >> >> Maybe worth mentioning both? > > I fear that would add more confusion than it avoids: > "!BAR" is actually different from "BAR=n", but *head explodes* > "BAR || !BAR" is the same as "BAR || BAR=n" here, and > trying to explain this in the documentation would either > make it incorrect or unhelpfully complicated. Fair enough. BR, Jani. -- Jani Nikula, Intel
