YongHyeon PYUN <pyu...@gmail.com> wrote: > On Wed, Oct 12, 2011 at 10:07:02AM -0400, Karim wrote: > > ... why are we ORing the same call twice isn't the same thing > > as calling it once: > > > > bmsr = PHY_READ(sc, E1000_SR) | PHY_READ(sc, E1000_SR); > > The E1000_SR_LINK_STATUS bit is latched low so it should be read > twice.
It might not be a bad idea to check the generated code to be sure that the read _is_ being done twice. An optimizer might well come to the same conclusion as Karim, and discard the "redundant" second instance (unless there's a "volatile" declaration somewhere in the expansion of PHY_READ, to explicitly indicate that it has side effects). _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
