Everything except for Bluetooth (and the obvious lack of free boot firmware) works, at least on the one I used (B40-80 80F6).

As is common for Lenovo the BIOS probably blocks other WiFi cards (didn't test). Semi-fortunately, the vendor-provided card is a WiFi+Bluetooth AR9565+AR3012 (M.2 form factor).

All the multimedia and hardware control keys also seem to work out of the box.

# lspci -nn
00:00.0 Host bridge [0600]: Intel Corporation Broadwell-U Host Bridge -OPI [8086:1604] (rev 09)
00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics 5500 [8086:1616] (rev 09)
00:03.0 Audio device [0403]: Intel Corporation Broadwell-U Audio Controller [8086:160c] (rev 09)
00:14.0 USB controller [0c03]: Intel Corporation Wildcat Point-LP USB xHCI Controller [8086:9cb1] (rev 03)
00:16.0 Communication controller [0780]: Intel Corporation Wildcat Point-LP MEI Controller #1 [8086:9cba] (rev 03)
00:1b.0 Audio device [0403]: Intel Corporation Wildcat Point-LP High Definition Audio Controller [8086:9ca0] (rev 03)
00:1c.0 PCI bridge [0604]: Intel Corporation Wildcat Point-LP PCI Express Root Port #1 [8086:9c90] (rev e3)
00:1c.1 PCI bridge [0604]: Intel Corporation Wildcat Point-LP PCI Express Root Port #2 [8086:9c92] (rev e3)
00:1c.2 PCI bridge [0604]: Intel Corporation Wildcat Point-LP PCI Express Root Port #3 [8086:9c94] (rev e3)
00:1c.3 PCI bridge [0604]: Intel Corporation Wildcat Point-LP PCI Express Root Port #4 [8086:9c96] (rev e3)
00:1d.0 USB controller [0c03]: Intel Corporation Wildcat Point-LP USB EHCI Controller [8086:9ca6] (rev 03)
00:1f.0 ISA bridge [0601]: Intel Corporation Wildcat Point-LP LPC Controller [8086:9cc5] (rev 03)
00:1f.2 SATA controller [0106]: Intel Corporation Wildcat Point-LP SATA Controller [AHCI Mode] [8086:9c83] (rev 03)
00:1f.3 SMBus [0c05]: Intel Corporation Wildcat Point-LP SMBus Controller [8086:9ca2] (rev 03)
02:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5229 PCI Express Card Reader [10ec:5229] (rev 01)
08:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 10)
09:00.0 Network controller [0280]: Qualcomm Atheros QCA9565 / AR9565 Wireless Network Adapter [168c:0036] (rev 01)

# lsusb

Bus 003 Device 002: ID 8087:8001 Intel Corp. 
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 006: ID 138a:0011 Validity Sensors, Inc. VFS5011 Fingerprint Reader
Bus 001 Device 004: ID 0cf3:3004 Atheros Communications, Inc. AR3012 Bluetooth 4.0
Bus 001 Device 003: ID 0bda:579c Realtek Semiconductor Corp. 
Bus 001 Device 002: ID 0930:6544 Toshiba Corp. TransMemory-Mini / Kingston DataTraveler 2.0 Stick
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub