Score:0

Having disabled a BCM43142A0 Bluetooth adapter, how do I remove the proprietary kernel blob?

kw flag

I've successfully disabled my laptop's internal Broadcom Bluetooth adapter using this procedure. All is now working fine with my replacement (non-Broadcom) external Bluetooth adapter. However, I think the now-disabled adapter was probably being driven by a proprietary kernel blob that I installed a long time ago with b43-fwcutter. Can I safely remove that blob, and if so how, please?

Jeremy31 avatar
ke flag
The b43-fwcutter is just a way to install Broadcom wifi firmware, it shouldn't cause any issues. Do you want to disable the Broadcom wifi?
Daniel Hatton avatar
kw flag
@Jeremy31 Yes, in fact I've already disabled the Broadcom wifi. Bit hazy on how I did that, possibly by apt removing bcmwl-kernel-source. The Broadcom Bluetooth was unaffected by that, though.
chili555 avatar
cn flag
b43 firmware has nothing whatever to do with bluetooth.
Daniel Hatton avatar
kw flag
AH, OK. The manpage for b43-fwcutter just says it's for "Broadcom 43xx hardware", it forgets to specify "only the wifi bits". Nevertheless, I still (probably) find myself with a blob in my kernel from when I was using the wifi adapter, and would still kind of like to remove said blob.
chili555 avatar
cn flag
It is much easier to simply blacklist the module(s). Please run: `lsmod` and paste the result here and give us the link: http://paste.ubuntu.com
Daniel Hatton avatar
kw flag
@chili555 Thanks. That paste site appears to require an Ubuntu One account, and ISTR reading the Ubuntu One Terms of Use a couple of years ago and thinking "no way". I have bcma and (probably irrelevant) btbcm loaded.
Score:2
cn flag

I suggest that you blacklist bcma.

sudo -i
echo "blacklist bcma"  >>  /etc/modprobe.d/blacklist.conf
modprobe -r bcma
exit

Now check:

sudo lshw -C network

Your Broadcom wireless device should now appear as UNCLAIMED.

EDIT: Please try:

sudo modprobe -r bcma
sudo modprobe -r cfg80211
sudo update-initramfs -u

Reboot.

Daniel Hatton avatar
kw flag
It does indeed, thanks. I'll see later if the UNCLAIMED-ness survives a reboot (blacklisting sometimes seems to be ignored for modules that are loaded as dependencies of another module).
Daniel Hatton avatar
kw flag
Oof. After a reboot, the "UNCLAIMED" has gone away and lsmod reveals bcma is loaded again. I've checked, and the relevant line is definitely present in /etc/modprobe.d/blacklist.conf.
chili555 avatar
cn flag
Please check again: `lsmod` Are any of these loaded? cfg80211,mac80211,ssb,bcma,cordic or b43?
Daniel Hatton avatar
kw flag
Yes: cfg80211 and bcma.
chili555 avatar
cn flag
Please see my edit in a few moments.
Daniel Hatton avatar
kw flag
Thanks. Should I also add cfg80211 to blacklist.conf?
chili555 avatar
cn flag
Do you have another wireless device? USB, perhaps? Does it also depend on cfg80211?
Daniel Hatton avatar
kw flag
Ah: when I try to modprobe -r cfg80211, I get a complaint that the module is in use by 88x2bu, which does indeed relate to the chipset in my new USB wifi interface.
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