Warnings when compiling kernel

[Roderick]

Are they normal?

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cc  -c -O2 -pipe -fno-strict-aliasing  -std=c99  -Wall -Wredundant-decls 
-Wnested-externs -Wstrict-prototypes  -Wmissing-prototypes -Wpointer-arith 
-Winline -Wcast-qual  -Wundef -Wno-pointer-sign -fformat-extensions 
-Wmissing-include-dirs -fdiagnostics-show-option 
-Wno-error-tautological-compare -Wno-error-empty-body 
-Wno-error-parentheses-equality -Wno-error-unused-function   -nostdinc 
-I. -I/usr/src/sys -I/usr/src/sys/contrib/altq 
-I/usr/src/sys/contrib/libfdt -D_KERNEL -DHAVE_KERNEL_OPTION_HEADERS 
-include opt_global.h  -mno-aes -mno-avx -mno-mmx -mno-sse -msoft-float 
-ffreestanding -fstack-protector -Werror  /usr/src/sys/kern/kern_cpuset.c
/usr/src/sys/kern/kern_cpuset.c:637:16: warning: comparison of unsigned
       expression < 0 is always false [-Wtautological-compare]
         for (i = 0; i < (_NCPUWORDS - 1); i++) {
                     ~ ^ ~~~~~~~~~~~~~~~~
1 warning generated.