Vitaliy Makkoveev <mvs@openbsd.org> wrote:

> The IFXF_MBUF_64BIT flag affects only amd64. All other architectures
> still uses memory below 4G. See revision 1.61 of
> sys/arch/amd64/amd64/autoconf.c line 129.

I don't see how that matters, that's part of the mechanism for
providing memory to drivers.

The diff in question which adds BUS_DMA_64BIT is a declaration to
the higher-level code that _all_ chipsets supported by this driver can
work with 64 bit-addressable memory if the higher levels provide it.

If one chipset can't do it, the experience will be terrible.