Broadcom-sta (aka wl) --> Error! Bad return status for module build on kernel

[Lukas Singer]

Hi Kernelnewbies,

i am doing the eudytpula challenge, currently on task #2.
it is about building your own kernel and booting it.

i successfully build the kernel and i am able to boot it but i have issues with my wlan driver.

when i run `$ sudo make install´ i get this error:
  Error! Bad return status for module build on kernel: 4.0.0-rc1-eudyptula-20150228+ (x86_64)
  Consult /var/lib/dkms/broadcom-sta/5.100.82.112/build/make.log for more information.

the make.log says:
  ...
  CFG80211 API is prefered for this kernel version
  Makefile:80: Neither CFG80211 nor Wireless Extension is enabled in kernel
  ...

but i have cfg80211 configured!
   ~/linux/linux $ cat .config | grep "CFG80211"
  CONFIG_CFG80211=y
  # CONFIG_CFG80211_DEVELOPER_WARNINGS is not set
  # CONFIG_CFG80211_REG_DEBUG is not set
  CONFIG_CFG80211_DEFAULT_PS=y
  # CONFIG_CFG80211_DEBUGFS is not set
  # CONFIG_CFG80211_INTERNAL_REGDB is not set
  CONFIG_CFG80211_WEXT=y

and i have wext configured!
   ~/linux/linux $ cat .config | grep "WEXT"
  CONFIG_WEXT_CORE=y
  CONFIG_WEXT_PROC=y
  CONFIG_WEXT_SPY=y
  CONFIG_WEXT_PRIV=y
  CONFIG_CFG80211_WEXT=y

although the kernel installs and boots, but wlan doesn't work.

i am on a debian system. lenovo edge e-135 notebook.
my current kernel comes from the official debian stable packages:
   ~/linux/linux $ uname -r
  3.2.0-4-amd64

this is my wlan device:
   ~/linux/linux $ lspci -nn | grep Network
  02:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller [14e4:4727] (rev 01)

i cannot go without wlan.
can anybody help?

thanks in advance,

lukas