Hi Bartlomiej, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: fb893de323e2d39f7a1f6df425703a2edbdf56ea commit: 3d3287e609877aa549b1cbb41eafaf73c3742a0b video: fbdev: arcfb: add COMPILE_TEST support date: 5 months ago config: riscv-randconfig-s031-20200812 (attached as .config) compiler: riscv64-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 # apt-get install sparse # sparse version: v0.6.2-168-g9554805c-dirty git checkout 3d3287e609877aa549b1cbb41eafaf73c3742a0b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=riscv If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) drivers/video/fbdev/arcfb.c:119:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:119:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:119:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:120:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:120:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:120:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:120:9: sparse: got void * drivers/video/fbdev/arcfb.c:122:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:122:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:122:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:122:9: sparse: got void * drivers/video/fbdev/arcfb.c:128:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:128:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:128:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:128:9: sparse: got void * drivers/video/fbdev/arcfb.c:134:16: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:134:16: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:134:16: sparse: expected void const volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:134:16: sparse: got void * drivers/video/fbdev/arcfb.c:142:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:142:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:142:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:142:9: sparse: got void * drivers/video/fbdev/arcfb.c:143:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:143:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:143:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:143:9: sparse: got void * drivers/video/fbdev/arcfb.c:145:9: sparse: sparse: cast removes address space '<asn:2>' of expression drivers/video/fbdev/arcfb.c:145:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void volatile [noderef] <asn:2> *addr @@ got void * @@ drivers/video/fbdev/arcfb.c:145:9: sparse: expected void volatile [noderef] <asn:2> *addr drivers/video/fbdev/arcfb.c:145:9: sparse: got void * vim +119 drivers/video/fbdev/arcfb.c 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 113 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 114 static void ks108_writeb_ctl(struct arcfb_par *par, 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 115 unsigned int chipindex, unsigned char value) 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 116 { 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 117 unsigned char chipselval = par->cslut[chipindex]; 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 118 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 @119 outb(chipselval|KS_CEHI|KS_SEL_CMD, par->cio_addr); 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 120 outb(value, par->dio_addr); 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 121 udelay(tuhold); 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 122 outb(chipselval|KS_CELO|KS_SEL_CMD, par->cio_addr); 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 123 } 1154ea7dcd8eed drivers/video/arcfb.c Jaya Kumar 2005-06-21 124 :::::: The code at line 119 was first introduced by commit :::::: 1154ea7dcd8eed758fb5ec47393a79d5a1f0bc43 [PATCH] Framebuffer driver for Arc LCD board :::::: TO: Jaya Kumar <jayalk(a)intworks.biz&gt; :::::: CC: Linus Torvalds <torvalds(a)ppc970.osdl.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org