of what uart(4) is and/or is not see the initial commit log of one
of the files in sys/dev/uart (or see share/man/man4/uart.4).
Note that currently pc98 shares the MD file with i386. This needs
to change when pc98 support is fleshed-out to properly support the
various UARTs. A good example is sparc64 in this respect.
We build uart(4) as a module on all platforms. This may break
the ppc port. That depends on whether they do actually build
modules.
To use uart(4) on alpha, one must use the NO_SIO option.
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