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 \
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 ${NO_WFORMAT}
35 # External compilers may not support our format extensions. Allow them
36 # to be disabled. WARNING: format checking is disabled in this case.
37 .if ${MK_FORMAT_EXTENSIONS} == "no"
38 NO_WFORMAT= -Wno-format
40 FORMAT_EXTENSIONS= -fformat-extensions
44 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
45 # and above adds code to the entry and exit point of every function to align the
46 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
47 # per function call. While the 16-byte alignment may benefit micro benchmarks,
48 # it is probably an overall loss as it makes the code bigger (less efficient
49 # use of code cache tag lines) and uses more stack (less efficient use of data
50 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
51 # operations inside the kernel itself. These operations are exclusively
52 # reserved for user applications.
55 # Setting -mno-mmx implies -mno-3dnow
56 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
59 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
60 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
62 .if ${MACHINE_CPUARCH} == "i386"
63 .if ${COMPILER_TYPE} != "clang"
64 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
66 CFLAGS+= -mno-aes -mno-avx
68 CFLAGS+= -mno-mmx -mno-sse -msoft-float
72 .if ${MACHINE_CPUARCH} == "arm"
77 # For IA-64, we use r13 for the kernel globals pointer and we only use
78 # a very small subset of float registers for integer divides.
80 .if ${MACHINE_CPUARCH} == "ia64"
81 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
86 # For sparc64 we want the medany code model so modules may be located
87 # anywhere in the 64-bit address space. We also tell GCC to use floating
88 # point emulation. This avoids using floating point registers for integer
89 # operations which it has a tendency to do.
91 .if ${MACHINE_CPUARCH} == "sparc64"
92 CFLAGS+= -mcmodel=medany -msoft-float
97 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
98 # operations inside the kernel itself. These operations are exclusively
99 # reserved for user applications.
102 # Setting -mno-mmx implies -mno-3dnow
103 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
106 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
107 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
108 # (-mfpmath= is not supported)
110 .if ${MACHINE_CPUARCH} == "amd64"
111 .if ${COMPILER_TYPE} == "clang"
112 CFLAGS+= -mno-aes -mno-avx
114 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
115 -fno-asynchronous-unwind-tables
120 # For PowerPC we tell gcc to use floating point emulation. This avoids using
121 # floating point registers for integer operations which it has a tendency to do.
122 # Also explicitly disable Altivec instructions inside the kernel.
124 .if ${MACHINE_CPUARCH} == "powerpc"
125 CFLAGS+= -msoft-float -mno-altivec
130 # Use dot symbols on powerpc64 to make ddb happy
132 .if ${MACHINE_ARCH} == "powerpc64"
133 CFLAGS+= -mcall-aixdesc
137 # For MIPS we also tell gcc to use floating point emulation
139 .if ${MACHINE_CPUARCH} == "mips"
140 CFLAGS+= -msoft-float
145 # GCC 3.0 and above like to do certain optimizations based on the
146 # assumption that the program is linked against libc. Stop this.
148 CFLAGS+= -ffreestanding
153 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
154 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
155 CFLAGS+= -fstack-protector