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Re: non-free software requirement



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


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