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 -Wno-error-unused-function \
36 .if ${COMPILER_TYPE} == "gcc"
37 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
38 CWARNEXTRA?= -Wno-uninitialized
41 # External compilers may not support our format extensions. Allow them
42 # to be disabled. WARNING: format checking is disabled in this case.
43 .if ${MK_FORMAT_EXTENSIONS} == "no"
44 NO_WFORMAT= -Wno-format
46 FORMAT_EXTENSIONS= -fformat-extensions
50 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
51 # and above adds code to the entry and exit point of every function to align the
52 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
53 # per function call. While the 16-byte alignment may benefit micro benchmarks,
54 # it is probably an overall loss as it makes the code bigger (less efficient
55 # use of code cache tag lines) and uses more stack (less efficient use of data
56 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
57 # operations inside the kernel itself. These operations are exclusively
58 # reserved for user applications.
61 # Setting -mno-mmx implies -mno-3dnow
62 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
65 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
66 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
68 .if ${MACHINE_CPUARCH} == "i386"
69 .if ${COMPILER_TYPE} != "clang"
70 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
72 CFLAGS+= -mno-aes -mno-avx
74 CFLAGS+= -mno-mmx -mno-sse -msoft-float
78 .if ${MACHINE_CPUARCH} == "arm"
83 # For IA-64, we use r13 for the kernel globals pointer and we only use
84 # a very small subset of float registers for integer divides.
86 .if ${MACHINE_CPUARCH} == "ia64"
87 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
92 # For sparc64 we want the medany code model so modules may be located
93 # anywhere in the 64-bit address space. We also tell GCC to use floating
94 # point emulation. This avoids using floating point registers for integer
95 # operations which it has a tendency to do.
97 .if ${MACHINE_CPUARCH} == "sparc64"
98 .if ${COMPILER_TYPE} == "clang"
99 CFLAGS+= -mcmodel=large -fno-dwarf2-cfi-asm
101 CFLAGS+= -mcmodel=medany -msoft-float
107 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
108 # operations inside the kernel itself. These operations are exclusively
109 # reserved for user applications.
112 # Setting -mno-mmx implies -mno-3dnow
113 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
116 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
117 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
118 # (-mfpmath= is not supported)
120 .if ${MACHINE_CPUARCH} == "amd64"
121 .if ${COMPILER_TYPE} == "clang"
122 CFLAGS+= -mno-aes -mno-avx
124 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
125 -fno-asynchronous-unwind-tables
130 # For PowerPC we tell gcc to use floating point emulation. This avoids using
131 # floating point registers for integer operations which it has a tendency to do.
132 # Also explicitly disable Altivec instructions inside the kernel.
134 .if ${MACHINE_CPUARCH} == "powerpc"
135 CFLAGS+= -msoft-float -mno-altivec
140 # Use dot symbols on powerpc64 to make ddb happy
142 .if ${MACHINE_ARCH} == "powerpc64"
143 CFLAGS+= -mcall-aixdesc
147 # For MIPS we also tell gcc to use floating point emulation
149 .if ${MACHINE_CPUARCH} == "mips"
150 CFLAGS+= -msoft-float
155 # GCC 3.0 and above like to do certain optimizations based on the
156 # assumption that the program is linked against libc. Stop this.
158 CFLAGS+= -ffreestanding
163 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
164 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
165 CFLAGS+= -fstack-protector
169 # Add -gdwarf-2 when compiling -g
171 .if ${COMPILER_TYPE} == "clang" && ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf} == ""