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 ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "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 # Several other warnings which might be useful in some cases, but not severe
28 # enough to error out the whole kernel build. Display them anyway, so there is
29 # some incentive to fix them eventually.
30 CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
31 -Wno-error-parentheses-equality
35 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
36 # and above adds code to the entry and exit point of every function to align the
37 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
38 # per function call. While the 16-byte alignment may benefit micro benchmarks,
39 # it is probably an overall loss as it makes the code bigger (less efficient
40 # use of code cache tag lines) and uses more stack (less efficient use of data
41 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
42 # operations inside the kernel itself. These operations are exclusively
43 # reserved for user applications.
46 # Setting -mno-mmx implies -mno-3dnow
47 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
50 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
51 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
53 .if ${MACHINE_CPUARCH} == "i386"
54 .if ${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang"
55 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
57 CFLAGS+= -mno-aes -mno-avx
59 CFLAGS+= -mno-mmx -mno-sse -msoft-float
63 .if ${MACHINE_CPUARCH} == "arm"
68 # For IA-64, we use r13 for the kernel globals pointer and we only use
69 # a very small subset of float registers for integer divides.
71 .if ${MACHINE_CPUARCH} == "ia64"
72 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
77 # For sparc64 we want the medany code model so modules may be located
78 # anywhere in the 64-bit address space. We also tell GCC to use floating
79 # point emulation. This avoids using floating point registers for integer
80 # operations which it has a tendency to do.
82 .if ${MACHINE_CPUARCH} == "sparc64"
83 CFLAGS+= -mcmodel=medany -msoft-float
88 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
89 # operations inside the kernel itself. These operations are exclusively
90 # reserved for user applications.
93 # Setting -mno-mmx implies -mno-3dnow
94 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
97 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
98 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
99 # (-mfpmath= is not supported)
101 .if ${MACHINE_CPUARCH} == "amd64"
102 .if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
103 CFLAGS+= -mno-aes -mno-avx
105 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
106 -fno-asynchronous-unwind-tables
111 # For PowerPC we tell gcc to use floating point emulation. This avoids using
112 # floating point registers for integer operations which it has a tendency to do.
113 # Also explicitly disable Altivec instructions inside the kernel.
115 .if ${MACHINE_CPUARCH} == "powerpc"
116 CFLAGS+= -msoft-float -mno-altivec
121 # Use dot symbols on powerpc64 to make ddb happy
123 .if ${MACHINE_ARCH} == "powerpc64"
124 CFLAGS+= -mcall-aixdesc
128 # For MIPS we also tell gcc to use floating point emulation
130 .if ${MACHINE_CPUARCH} == "mips"
131 CFLAGS+= -msoft-float
136 # GCC 3.0 and above like to do certain optimizations based on the
137 # assumption that the program is linked against libc. Stop this.
139 CFLAGS+= -ffreestanding
144 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
145 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
146 CFLAGS+= -fstack-protector
150 # Enable CTF conversation on request
152 .if defined(WITH_CTF)