miivar.h includes opt_platform.h. Make sure all the drivers that use the
miibus_if.h interface file have opt_platform.h as well. While some of
these may not, strictly speaking, need it, it's easier to include it
universally for miibus.
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drivers that only ever attach to a particular MAC driver, i.e. inphy(4),
ruephy(4) and xlphy(4), to the directory where the respective MAC driver
lives and only compile it into the kernel when the latter is also there,
also removing it from miibus.ko and moving it into the module of the
respective MAC driver.
- While at it, rename exphy.c, which comes from NetBSD where the MAC driver
it corresponds to also is named ex(4) instead of xl(4) but that in FreeBSD
actually identifies itself as xlphy(4), and its function names accordingly
for consistency.
- Additionally while at it, fix some minor style issues like whitespace
in the register headers and add multi-inclusion protection to inphyreg.h.
