gigE negotiation failure with wm0

["Steven M. Bellovin" <smb%cs.columbia.edu@localhost>]

On my laptop (Thinkpad T61 running amd64-current), if I connect it to a
NETGEAR GS608 Gigabit switch, it speaks properly at 1000M bps.  If,
however, I connect it to a NETGEAR GS108 ProSafe switch, it can only
negotiate 10M bps, though it will talk at 100M bps if I configure it
manually.  Power-cycling the switch doesn't help, nor do switching
cables or ports.  Ubuntu 8.04 speaks GigE just fine on the exact same
hardware, so I suspect a driver issue.

Here are the wm0 and phy lines from dmesg:

wm0 at pci0 dev 25 function 0: Intel i82801H (M_AMT) LAN Controller,
rev. 3 wm0: interrupting at ioapic0 pin 20 (irq 11)
wm0: PCI-Express bus
wm0: FLASH
wm0: Ethernet address 00:1e:37:18:93:c5
igphy0 at wm0 phy 1: i82566 10/100/1000 media interface, rev. 0
igphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT,
1000baseT-FDX, auto