Hi Srivatsa, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on vhost/linux-next] [also build test WARNING on xen-tip/linux-next linus/master v5.7-rc3 next-20200428] [cannot apply to swiotlb/linux-next] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Srivatsa-Vaddagiri/virtio-on-Type-1-hypervisor/20200429-032334 base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next config: sh-randconfig-a001-20200428 (attached as .config) compiler: sh4-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=sh If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot All warnings (new ones prefixed by >>): In file included from drivers/virtio/virtio_bounce.c:13: include/linux/swiotlb.h: In function 'swiotlb_alloc': include/linux/swiotlb.h:234:9: error: 'DMA_MAPPING_ERROR' undeclared (first use in this function) 234 | return DMA_MAPPING_ERROR; | ^~~~~~~~~~~~~~~~~ include/linux/swiotlb.h:234:9: note: each undeclared identifier is reported only once for each function it appears in >> include/linux/swiotlb.h:235:1: warning: control reaches end of non-void function [-Wreturn-type] 235 | } | ^ vim +235 include/linux/swiotlb.h 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 229 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 230 static inline phys_addr_t swiotlb_alloc(struct swiotlb_pool *pool, 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 231 size_t alloc_size, unsigned long tbl_dma_addr, 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 232 unsigned long mask) 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 233 { 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 234 return DMA_MAPPING_ERROR; 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 @235 } 9ab4c39d9f9298 Srivatsa Vaddagiri 2020-04-28 236 :::::: The code at line 235 was first introduced by commit :::::: 9ab4c39d9f929840cb884e589f6112770dbc2f63 swiotlb: Add alloc and free APIs :::::: TO: Srivatsa Vaddagiri :::::: CC: 0day robot --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org