4 # Warning flags for compiling the kernel and components of the kernel:
6 CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
7 -Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
8 -Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
9 -Wmissing-include-dirs -fdiagnostics-show-option \
13 # The following flags are next up for working on:
16 # Disable a few warnings for clang, since there are several places in the
17 # kernel where fixing them is more trouble than it is worth, or where there is
19 .if ${COMPILER_TYPE} == "clang"
20 NO_WCONSTANT_CONVERSION= -Wno-constant-conversion
21 NO_WARRAY_BOUNDS= -Wno-array-bounds
22 NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
23 NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
24 NO_WUNUSED_VALUE= -Wno-unused-value
25 NO_WSELF_ASSIGN= -Wno-self-assign
26 NO_WFORMAT_SECURITY= -Wno-format-security
27 NO_WUNNEEDED_INTERNAL_DECL= -Wno-unneeded-internal-declaration
28 NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
29 # Several other warnings which might be useful in some cases, but not severe
30 # enough to error out the whole kernel build. Display them anyway, so there is
31 # some incentive to fix them eventually.
32 CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
33 -Wno-error-parentheses-equality -Wno-error-unused-function \
37 # External compilers may not support our format extensions. Allow them
38 # to be disabled. WARNING: format checking is disabled in this case.
39 .if ${MK_FORMAT_EXTENSIONS} == "no"
40 NO_WFORMAT= -Wno-format
42 FORMAT_EXTENSIONS= -fformat-extensions
46 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
47 # and above adds code to the entry and exit point of every function to align the
48 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
49 # per function call. While the 16-byte alignment may benefit micro benchmarks,
50 # it is probably an overall loss as it makes the code bigger (less efficient
51 # use of code cache tag lines) and uses more stack (less efficient use of data
52 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
53 # operations inside the kernel itself. These operations are exclusively
54 # reserved for user applications.
57 # Setting -mno-mmx implies -mno-3dnow
58 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
61 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
62 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
64 .if ${MACHINE_CPUARCH} == "i386"
65 .if ${COMPILER_TYPE} != "clang"
66 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
68 CFLAGS+= -mno-aes -mno-avx
70 CFLAGS+= -mno-mmx -mno-sse -msoft-float
74 .if ${MACHINE_CPUARCH} == "arm"
79 # For IA-64, we use r13 for the kernel globals pointer and we only use
80 # a very small subset of float registers for integer divides.
82 .if ${MACHINE_CPUARCH} == "ia64"
83 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
88 # For sparc64 we want the medany code model so modules may be located
89 # anywhere in the 64-bit address space. We also tell GCC to use floating
90 # point emulation. This avoids using floating point registers for integer
91 # operations which it has a tendency to do.
93 .if ${MACHINE_CPUARCH} == "sparc64"
94 .if ${COMPILER_TYPE} == "clang"
95 CFLAGS+= -mcmodel=large -fno-dwarf2-cfi-asm
97 CFLAGS+= -mcmodel=medany -msoft-float
103 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
104 # operations inside the kernel itself. These operations are exclusively
105 # reserved for user applications.
108 # Setting -mno-mmx implies -mno-3dnow
109 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
112 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
113 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
114 # (-mfpmath= is not supported)
116 .if ${MACHINE_CPUARCH} == "amd64"
117 .if ${COMPILER_TYPE} == "clang"
118 CFLAGS+= -mno-aes -mno-avx
120 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
121 -fno-asynchronous-unwind-tables
126 # For PowerPC we tell gcc to use floating point emulation. This avoids using
127 # floating point registers for integer operations which it has a tendency to do.
128 # Also explicitly disable Altivec instructions inside the kernel.
130 .if ${MACHINE_CPUARCH} == "powerpc"
131 CFLAGS+= -msoft-float -mno-altivec
136 # Use dot symbols on powerpc64 to make ddb happy
138 .if ${MACHINE_ARCH} == "powerpc64"
139 CFLAGS+= -mcall-aixdesc
143 # For MIPS we also tell gcc to use floating point emulation
145 .if ${MACHINE_CPUARCH} == "mips"
146 CFLAGS+= -msoft-float
151 # GCC 3.0 and above like to do certain optimizations based on the
152 # assumption that the program is linked against libc. Stop this.
154 CFLAGS+= -ffreestanding
159 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
160 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
161 CFLAGS+= -fstack-protector
165 # Add -gdwarf-2 when compiling -g
167 .if ${COMPILER_TYPE} == "clang" && ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf} == ""