Re: fs: dax: do not build on ARC or SH

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Feb 23, 2015 at 01:40:25PM -0500, Matthew Wilcox wrote:
> On Mon, Feb 23, 2015 at 12:29:45PM +0100, Arnd Bergmann wrote:
> > The DAX implementation relies on the architecture to provide a working
> > copy_user_page() function, as reported by Michael Ellerman's kisskb
> > build bot:
> > 
> > fs/dax.c: error: implicit declaration of function 'copy_user_page' [-Werror=implicit-function-declaration]:  => 266:2
> > 
> > We already have a list of architectures that are known to be incompatible,
> > but the list is missing ARC and SH at the moment. Further, blackfin and
> > c6x also lack support for this function, but are already excluded because
> > they do not support MMU-based kernels.
> 
> I've got a short list of patches for DAX; I'll add this one to the list.
> 
> Have the maintainers of these architectures been notified that they're
> missing a core piece of kernel functionality?
> 

Guess there a philosophical difference in opinion if the architecture code
should (have to) provide copy_user_page() or not outside the architecture
code itself. After all, fs/dax.c _is_ the only user of this function outside
the architecture code.

Guenter