Re: [PATCH net-next V2] net: ks8851: Fix mixed module/builtin build

On Sat, Jan 16, 2021 at 08:26:22PM +0100, Arnd Bergmann wrote:

On Sat, Jan 16, 2021 at 6:56 PM Marek Vasut [off-list ref] wrote:

quoted

On 1/16/21 6:04 PM, Arnd Bergmann wrote:

quoted

On Sat, Jan 16, 2021 at 5:48 PM Marek Vasut [off-list ref] wrote:

quoted

I don't really like this version, as it does not actually solve the problem of
linking the same object file into both vmlinux and a loadable module, which
can have all kinds of side-effects besides that link failure you saw.

If you want to avoid exporting all those symbols, a simpler hack would
be to '#include "ks8851_common.c" from each of the two files, which
then always duplicates the contents (even when both are built-in), but
at least builds the file the correct way.

That's the same as V1, isn't it ?

Ah, I had not actually looked at the original submission, but yes, that
was slightly better than v2, provided you make all symbols static to
avoid the new link error.

I still think that having three modules and exporting the symbols from
the common part as Heiner Kallweit suggested would be the best
way to do it.

FWIW I'd prefer V1 (the #include approach) as it allows going back to
using static inlines for register access.  That's what we had before
7a552c850c45.

It seems unlikely that a system uses both, the parallel *and* the SPI
variant of the ks8851.  So the additional memory necessary because of
code duplication wouldn't matter in practice.

Thanks,

Lukas