Hi Dan, On Tue, May 9, 2017 at 12:36 AM, kbuild test robot <lkp@xxxxxxxxx> wrote: > [auto build test ERROR on linus/master] > [also build test ERROR on next-20170508] > [cannot apply to v4.11] > [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > > url: https://github.com/0day-ci/linux/commits/Dan-Williams/block-dax-move-select-DAX-from-BLOCK-to-FS_DAX/20170509-051522 > config: parisc-c3000_defconfig (attached as .config) > compiler: hppa-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705 > reproduce: > wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > # save the attached .config to linux build tree > make.cross ARCH=parisc > > All errors (new ones prefixed by >>): > > fs/built-in.o: In function `bdev_dax_supported': >>> (.text.bdev_dax_supported+0x4c): undefined reference to `dax_get_by_host' > fs/built-in.o: In function `bdev_dax_supported': >>> (.text.bdev_dax_supported+0x5c): undefined reference to `dax_read_lock' > fs/built-in.o: In function `bdev_dax_supported': >>> (.text.bdev_dax_supported+0x7c): undefined reference to `dax_direct_access' > fs/built-in.o: In function `bdev_dax_supported': >>> (.text.bdev_dax_supported+0x88): undefined reference to `dax_read_unlock' > fs/built-in.o: In function `bdev_dax_supported': >>> (.text.bdev_dax_supported+0x90): undefined reference to `put_dax' I ran into the same issue if CONFIG_DAX=m (it's still selected by some other modular symbol). #if IS_ENABLED(CONFIG_DAX) is true in the modular case, so the dummies provided by include/linux/dax.h are not used. However, while changing it to #ifdef CONFIG_DAX allows to build vmlinux, it leads to other issues as DAX is compiled as a module: drivers/dax/super.c:35: error: redefinition of ‘dax_read_lock’ include/linux/dax.h:30: error: previous definition of ‘dax_read_lock’ was here Yes, calling into optional modular code from builtin code in fs/blockdev.c is tricky ;-( Perhaps you can make bdev_dax_supported() a small wrapper that calls into the real code through a function pointer, when the DAX module is available? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
