Syncing with 2.4.20-pre2
Gigabyte 7VKMLS Rev 4.0
Are you really sure it's RTL-8101?
I definitely have got a card with an 8100C chip and the same 8139 ID.
Table with full PCI ID; chip; MAC's vendor part; Card's name:
10ec:8139:11f6:8139 (Compex); 8139C; 00:C0:26 (Lans Technology); noname
10ec:8139:10ec:8139 (Realtek); 8139C; 00:C0:26 (Lans Technology); noname
10ec:8139:10ec:8139 (Realtek); 8139C; 00:50:22 (Zonet Technology); noname
10ec:8139:1259:2503 (Allied Telesis); 8139C; 00:30:84 (Allied Telesyn); AT-2500TX
10ec:8139:1113:ec01 (Accton); 8139B; 00:50:BF (Metalligence Technology); Level One FNC-0109TX
10ec:8139:10ec:8139 (Realtek); 8100C; 00:0A:CD (Sunrich Technology); noname
Carenas might have been correct, but I cannot verify that, so perhaps rename it to "RTL-81xx/B/C(+)"?
See also the subsystem discussions.
Name: RTL-8100/8101L/8139 PCI Fast Ethernet Adapter
I'd do it just like the 8111/8168; there I removed the B, C... letters. There also exists an 8100B according to Realtek website.
The RTL8139D probably uses this ID too (there are RTL8139D's known using device 8139 with different vendor ID 1904).