HelenOS sources

BMCR_SPD_100      602 uspace/drv/nic/rtl8169/driver.c 	bmcr &= ~(BMCR_DUPLEX | BMCR_SPD_100 | BMCR_SPD_1000);
BMCR_SPD_100      611 uspace/drv/nic/rtl8169/driver.c 		bmcr |= BMCR_SPD_100;
HelenOS homepage, sources at GitHub