Vendor driver vs Kernel, which one gets priority?

[Do Hak Yong]

Thank you so much for detailed advise!!

Best regards,

2022년 10월 20일 (목) 오전 2:03, Bjørn Mork <bjorn at mork.no>님이 작성:

> Do Hak Yong <crazyraven at gmail.com> writes:
>
> > Hello kernel experts,
> >
> > I have a few questions about the priority of kernel drivers and third
> party
> > drivers.
> >
> > If I install a third party vendor driver, which has the same module name
> as
> > kernel provides, for example, Qlogic driver has the same module name as
> > third party driver(qla2xxx).
> >
> > The questions are:
> >
> > Q1. Which driver has higher priority and which driver will be used? will
> > there any be problems?
>
> See depmod.d(5).
>
> Unless overridden by config, modules in /lib/modules/$(uname -r)/updates
> have priority over other modules.  This can be used to replace kernel
> modules with a third party driver.
>
> The third party driver could also use a startup script to forcibly
> replace already loaded modules.
>
> > Q2. How to control which driver the os will use?
>
> If the file names are identical, then use the "updates" directory or
> configure another location to have priority over the kernel modules.
>
> If the file names are different, then you can blacklist the kernel
> module to make sure the third party module is the only one available for
> auto-loading.  See modprobe.d(5)
>
> > Q3. What if the updated kernel installed and provied higher driver
> version
> > than third party? Which one will be used then?
>
> The default is to consider only the modules in /lib/modules/$(uname -r)
>
> Any third party module must be updated along with the kerne.  Or copied
> into the new location if binary compatible. But that's not likely in
> general.
>
> > I think third party drivers have more precedence that kernel drivers
> refer
> > to below Red Hat KB, but I'm not sure which one will be used when the
> > kernel has updated.
> >
> > https://access.redhat.com/solutions/176213
>
> Redhat uses a more complex depmod configuration than default.  You
> should probably ask them about their setup.  Or just look at the config
> in /etc/depmod.d/*.conf
>
>
> Bjørn
>
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