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From:   Krish Jain <krishjain02939@gmail.com>
Date:   Sun, 29 Aug 2021 18:56:50 +0200
Message-ID: <CAPGkw+ypKOVsJF_Guna+9+q-+cApYzdBGHMPKKr6MAzGQtqy2g@mail.gmail.com>
Subject: Re: [PATCH] Declare the file_operations struct as const
To:     Bryan Brattlof <hello@bryanbrattlof.com>
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
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On Sun, Aug 29, 2021 at 6:49 PM Bryan Brattlof <hello@bryanbrattlof.com> wr=
ote:
>
> On this day, August 29, 2021, thus sayeth Krish Jain:
> > > >
> > > > Hi, what option do you mean?  I already ran make allmodconfig and s=
udo
> > > > make modules_install install and then make   "CCFLAGS=3D-Werror W=
=3D1
> > > > M=3Ddrivers/staging/android/" and now I do get output but one line
> > > > "WARNING: Symbol version dump "Module.symvers" is missing. Modules =
may
> > > > not have dependencies or modversions. You may get many unresolved
> > > > symbol warnings." . Then I tried "make CCFLAGS=3D-Werror V=3D1
> > > > M=3Ddrivers/staging/android/" and that outputted the following:
> > > >
> > >
> > > Most of the answers you're asking for are going to get vague response=
s
> > > (if any) on the mailing lists. The idea being (and I agree with) that
> > > giving out the answers will steal your opportunity to explore and lea=
rn
> > > the material yourself.
> > >
> > > Yes, it would be faster if we told you the answer, but ultimately, we
> > > would be doing a disservice to you.
> > >
> > > Besides, more times than not we (me especially) don't have the answer=
.
> > >
> > > With that said, I will give a (generous) hint. :)
> > >
> >
> > Hi. Do I have to build the kernel once before this works? Or can I
> > just build a module directly?
> >
>
> Again, do not allow others to rob you of learning how to solve these
> issues yourself. I *strongly* encourage you to familiarize yourself with
> the Kernel Build System in the Documentation.
>
>   https://www.kernel.org/doc/html/latest/kbuild/modules.html
>
> Specifically the first paragraph of "2. How to Build External Modules"
>
> It may seem like a lot for such a simple issue but it *is* worth it.
> ~Bryan
>


That section says


"To build external modules, *you must have a prebuilt kernel
available* that contains the configuration and header files used in
the build. Also, the kernel must have been built with modules enabled.
If you are using a distribution kernel, there will be a package for
the kernel you are running provided by your distribution.

An alternative is to use the =E2=80=9Cmake=E2=80=9D target =E2=80=9Cmodules=
_prepare.=E2=80=9D This
will make sure the kernel contains the information required. The
target exists solely as a simple way to prepare a kernel source tree
for building external modules.

NOTE: =E2=80=9Cmodules_prepare=E2=80=9D will not build Module.symvers even =
if
CONFIG_MODVERSIONS is set; therefore, *a full kernel build needs to be
executed to make module versioning work.*"

So I am just trying to confirm with you whether I have to first build
the kernel with like "make" or not? As you can imagine my hardware
takes *very* long to build a kernel as I did in my last attempt so I
am asking whether it is needed. Hope you understand.

Best Regards