Hi, I am trying to build 64bit linux. .config file got created. But while compiling I get the error "unimplemented: 64-bit mode not compiled in". Any pointers much appreciated. Step2: bash-3.00$ make V=1 CC="gcc.c4.5.3-p0.linux" ARCH=x86_64 gcc.c4.5.3-p0.linux -Wp,-MD,kernel/.bounds.s.d -nostdinc -isystem /auto/sw/packages/gcc/c4.5.3-p0/i686-pc-linux/bin/../lib/gcc/i686-pc-linux/4.5.3/include -I/iws/grp-1/Linux_ker/linux-3.8.7/arch/x86/include -Iarch/x86/include/generated -Iinclude -I/iws/grp-1/Linux_ker/linux-3.8.7/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/iws/grp-1/Linux_ker/linux-3.8.7/include/uapi -Iinclude/generated/uapi -include /iws/grp-1/Linux_ker/linux-3.8.7/include/linux/kconfig.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -fno-delete-null-pointer-checks -O2 -m64 -mno-red-zone -mcmodel=kernel -maccumulate-outgoing-args -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_AVX=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -fno-optimize-sibling-calls -DCC_HAVE_ASM_GOTO -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(bounds)" -D"KBUILD_MODNAME=KBUILD_STR(bounds)" -fverbose-asm -S -o kernel/bounds.s kernel/bounds.c kernel/bounds.c:1:0: error: code model âkernelâ not supported in the 32 bit mode <===Error here kernel/bounds.c:1:0: sorry, unimplemented: 64-bit mode not compiled in <==== Error here make-3.79.1-p7[1]: *** [kernel/bounds.s] Error 1 make-3.79.1-p7: *** [prepare0] Error 2 bash-3.00$ Step1: bash-3.00$ make V=1 CC="gcc.c4.5.3-p0.x86elf" ARCH=x86_64 x86_64_defconfig make-3.79.1-p7 -f scripts/Makefile.build obj=scripts/basic rm -f .tmp_quiet_recordmcount mkdir -p include/linux include/config make-3.79.1-p7 -f scripts/Makefile.build obj=scripts/kconfig x86_64_defconfig scripts/kconfig/conf --defconfig=arch/x86/configs/x86_64_defconfig Kconfig # # configuration written to .config #