em0: <Intel(R) PRO/1000 Legacy Network Connection 1.0.6> mem 0xfe680000-0xfe69ffff,0xfe660000-0xfe67ffff irq 48 at device 2.0 on pci5
em0: 0x20 bytes of rid 0x20 res 4 failed (0, 0xffffffff).
em0: Unable to allocate bus resource: ioport
em0: Allocation of PCI resources failed
device_attach: em0 attach returned 6
其實不只出現在 em，ahc 也出現類似的訊息：
ahc0: <Adaptec aic7899 Ultra160 SCSI adapter> mem 0xfe8fe000-0xfe8fefff irq 72 at device 6.0 on pci7
ahc0: 0x100 bytes of rid 0x10 res 4 failed (0, 0xffffffff).
ahc0: can't allocate register resources
device_attach: ahc0 attach returned 12
