I've got an emachines T1440 with four usb ports (two on the front, two
on the back).  However, the usb probing runs into problems.  On a
regular boot (with no u*debug variables set), the resulting dmesg is:
[...]
rtk0 at pci1 dev 6 function 0: RealTek 8139 10/100BaseTX
rtk0: interrupting at irq 11
rtk0: Ethernet address 00:40:2b:3d:3d:36
ukphy0 at rtk0 phy 7: Generic IEEE 802.3u media interface
ukphy0: OUI 0x000000, model 0x0000, rev. 0
ukphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
[...]
uhci0 at pci0 dev 31 function 2: Intel 82801AA USB Controller (rev. 0x02)
uhci0: interrupting at irq 11
usb0 at uhci0: USB revision 1.0
uhub0 at usb0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
Intel 82801AA SMBus Controller (SMBus serial bus, revision 0x02) at pci0 dev 31 function 3 not configured
[...]
uhub1 at uhub0 port 2
uhub1: vendor 0x109f product 0x7148, class 9/0, rev 1.10/0.00, addr 2
boot device: wd0
[...]