Re: VirtualBox module build breakage since commit 39808e451fdf

[Larry Finger]

On 12/15/19 11:11 PM, Masahiro Yamada wrote:
> Hi.
>
> On Mon, Dec 16, 2019 at 11:48 AM Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote:
> > Hi,
> >
> > Since commit 39808e451fdf ("kbuild: do not read
> > $(KBUILD_EXTMOD)/Module.symvers"), some of the modules for VirtualBox have
> > failed to build. There are at least 3 such modules, namely vboxdrv, vboxnetflt,
> > and vboxnetadp.
>
> As the section 6.3 of Documentation/kbuild/modules.rst says,
> the best practice is to put the related modules into the same source
> tree, and then do like this:
>
>    obj-m := vboxdrv/  vboxnetfit/  vboxnetadp/
>
>
>
> If you want to maintain the three separately,
> as 39808e451fdf mentions, you can useKBUILD_EXTRA_SYMBOLS.
> KBUILD_EXTRA_SYMBOLS was added more than a decade.
> So, you should be able to use it for your modules.
>
> I think it is a cleaner solution than
> copying around Module.symvers in your build tree.

Masahiro,

Thank you for your prompt reply. Once I got it right, the KBUILD_EXTRA_SYMBOLS 
method works. The debugging was slow due to the problem area happening near the 
end of a 45-minute build, but I now have a solution that works for all kernels.

Thanks again,

Larry