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 -fformat-extensions \
9 -Wmissing-include-dirs -fdiagnostics-show-option \
12 # The following flags are next up for working on:
15 # Disable a few warnings for clang, since there are several places in the
16 # kernel where fixing them is more trouble than it is worth, or where there is
18 .if ${COMPILER_TYPE} == "clang"
19 NO_WCONSTANT_CONVERSION= -Wno-constant-conversion
20 NO_WARRAY_BOUNDS= -Wno-array-bounds
21 NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
22 NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
23 NO_WUNUSED_VALUE= -Wno-unused-value
24 NO_WSELF_ASSIGN= -Wno-self-assign
25 NO_WFORMAT_SECURITY= -Wno-format-security
26 NO_WUNNEEDED_INTERNAL_DECL= -Wno-unneeded-internal-declaration
27 NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
28 # Several other warnings which might be useful in some cases, but not severe
29 # enough to error out the whole kernel build. Display them anyway, so there is
30 # some incentive to fix them eventually.
31 CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
32 -Wno-error-parentheses-equality
36 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
37 # and above adds code to the entry and exit point of every function to align the
38 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
39 # per function call. While the 16-byte alignment may benefit micro benchmarks,
40 # it is probably an overall loss as it makes the code bigger (less efficient
41 # use of code cache tag lines) and uses more stack (less efficient use of data
42 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
43 # operations inside the kernel itself. These operations are exclusively
44 # reserved for user applications.
47 # Setting -mno-mmx implies -mno-3dnow
48 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
51 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
52 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
54 .if ${MACHINE_CPUARCH} == "i386"
55 .if ${COMPILER_TYPE} != "clang"
56 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
58 CFLAGS+= -mno-aes -mno-avx
60 CFLAGS+= -mno-mmx -mno-sse -msoft-float
64 .if ${MACHINE_CPUARCH} == "arm"
69 # For IA-64, we use r13 for the kernel globals pointer and we only use
70 # a very small subset of float registers for integer divides.
72 .if ${MACHINE_CPUARCH} == "ia64"
73 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
78 # For sparc64 we want the medany code model so modules may be located
79 # anywhere in the 64-bit address space. We also tell GCC to use floating
80 # point emulation. This avoids using floating point registers for integer
81 # operations which it has a tendency to do.
83 .if ${MACHINE_CPUARCH} == "sparc64"
84 CFLAGS+= -mcmodel=medany -msoft-float
89 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
90 # operations inside the kernel itself. These operations are exclusively
91 # reserved for user applications.
94 # Setting -mno-mmx implies -mno-3dnow
95 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
98 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
99 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
100 # (-mfpmath= is not supported)
102 .if ${MACHINE_CPUARCH} == "amd64"
103 .if ${COMPILER_TYPE} == "clang"
104 CFLAGS+= -mno-aes -mno-avx
106 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
107 -fno-asynchronous-unwind-tables
112 # For PowerPC we tell gcc to use floating point emulation. This avoids using
113 # floating point registers for integer operations which it has a tendency to do.
114 # Also explicitly disable Altivec instructions inside the kernel.
116 .if ${MACHINE_CPUARCH} == "powerpc"
117 CFLAGS+= -msoft-float -mno-altivec
122 # Use dot symbols on powerpc64 to make ddb happy
124 .if ${MACHINE_ARCH} == "powerpc64"
125 CFLAGS+= -mcall-aixdesc
129 # For MIPS we also tell gcc to use floating point emulation
131 .if ${MACHINE_CPUARCH} == "mips"
132 CFLAGS+= -msoft-float
137 # GCC 3.0 and above like to do certain optimizations based on the
138 # assumption that the program is linked against libc. Stop this.
140 CFLAGS+= -ffreestanding
145 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
146 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
147 CFLAGS+= -fstack-protector