On Thu, Dec 08, 2016 at 08:34:49PM +0100, Yvan Masson wrote: > So, from the result of: > # dmesg | grep firmware > -> you know that kernel module "b43" is missing some firmware > (ucode15.fw) > > After enabling contrib and non-free repository, you can search for > related packages: > $ apt search b43 > This lists interesting packages: "firmware-b43-installer" and > "firmware-b43legacy-installer". > > Next run: > $ apt show firmware-b43-installer > and > $ apt show firmware-b43legacy-installer > -> this show that these packages are useful for different chipsets, so > you need to know which one is in you laptop. > > As pointed Henrique de Moraes, you can run "lspci" for that: > … > Network controller: Broadcom Corporation BCM4312 802.11b/g LP-PHY (rev > 01) > … > > So, finally, if you see that this device is not working well, you can > install "firmware-b43-installer" :-) > > Then reboot you computer to check that errors from dmesg have > disappeared. > All true, BUT... The stock Debian kernel contains a lot of device drivers that aren't necessarily needed for your particular setup. This is the only way it can work in a large number of different systems. Most of these drivers are compiled as modules and hence SHOULD only be getting loaded if actually needed, but two things can go wrong with that: 1) some drivers, for esoteric reasons, don't work as modules and have to be compiled into the kernel image, 2) udev rules may have subtle flaws that cause drivers that are not needed to be loaded when hardware is detected.
So, if your computer is generally working it's possible that the device driver that is complaining about missing firmware is actually a driver you don't need... and if that turns out to be the case, you have the option to ignore the warnings. The other option is to blacklist the device driver module (if it IS a module) to prevent it being loaded -- no module load, no complaints. On my Jessie install, there are several complaints about missing firmware for drivers for hardware I don't have... I ignore them. If memory were tight I might look into suppressing the drivers from being loaded, but it isn't, and the drivers aren't doing any harm, so I ignore them on the basis that if I leave them alone, they seem to leave me alone. Mark