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 \
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-unused-function
37 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
38 # and above adds code to the entry and exit point of every function to align the
39 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
40 # per function call. While the 16-byte alignment may benefit micro benchmarks,
41 # it is probably an overall loss as it makes the code bigger (less efficient
42 # use of code cache tag lines) and uses more stack (less efficient use of data
43 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
44 # operations inside the kernel itself. These operations are exclusively
45 # reserved for user applications.
48 # Setting -mno-mmx implies -mno-3dnow
49 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
52 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
53 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
55 .if ${MACHINE_CPUARCH} == "i386"
56 .if ${COMPILER_TYPE} != "clang"
57 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
59 CFLAGS+= -mno-aes -mno-avx
61 CFLAGS+= -mno-mmx -mno-sse -msoft-float
65 .if ${MACHINE_CPUARCH} == "arm"
70 # For IA-64, we use r13 for the kernel globals pointer and we only use
71 # a very small subset of float registers for integer divides.
73 .if ${MACHINE_CPUARCH} == "ia64"
74 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
79 # For sparc64 we want the medany code model so modules may be located
80 # anywhere in the 64-bit address space. We also tell GCC to use floating
81 # point emulation. This avoids using floating point registers for integer
82 # operations which it has a tendency to do.
84 .if ${MACHINE_CPUARCH} == "sparc64"
85 .if ${COMPILER_TYPE} == "clang"
86 CFLAGS+= -mcmodel=large -fno-dwarf2-cfi-asm
88 CFLAGS+= -mcmodel=medany -msoft-float
94 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
95 # operations inside the kernel itself. These operations are exclusively
96 # reserved for user applications.
99 # Setting -mno-mmx implies -mno-3dnow
100 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
103 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
104 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
105 # (-mfpmath= is not supported)
107 .if ${MACHINE_CPUARCH} == "amd64"
108 .if ${COMPILER_TYPE} == "clang"
109 CFLAGS+= -mno-aes -mno-avx
111 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
112 -fno-asynchronous-unwind-tables
117 # For PowerPC we tell gcc to use floating point emulation. This avoids using
118 # floating point registers for integer operations which it has a tendency to do.
119 # Also explicitly disable Altivec instructions inside the kernel.
121 .if ${MACHINE_CPUARCH} == "powerpc"
122 CFLAGS+= -msoft-float -mno-altivec
127 # Use dot symbols on powerpc64 to make ddb happy
129 .if ${MACHINE_ARCH} == "powerpc64"
130 CFLAGS+= -mcall-aixdesc
134 # For MIPS we also tell gcc to use floating point emulation
136 .if ${MACHINE_CPUARCH} == "mips"
137 CFLAGS+= -msoft-float
142 # GCC 3.0 and above like to do certain optimizations based on the
143 # assumption that the program is linked against libc. Stop this.
145 CFLAGS+= -ffreestanding
150 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
151 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
152 CFLAGS+= -fstack-protector