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 \
10 -Wno-unknown-pragmas \
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_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
22 NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
23 NO_WSELF_ASSIGN= -Wno-self-assign
24 NO_WUNNEEDED_INTERNAL_DECL= -Wno-unneeded-internal-declaration
25 NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
26 NO_WCAST_QUAL= -Wno-cast-qual
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 -Wno-error-unused-function \
32 -Wno-error-pointer-sign
33 .if ${COMPILER_VERSION} >= 30700
34 CWARNEXTRA+= -Wno-error-shift-negative-value
37 CLANG_NO_IAS= -no-integrated-as
38 .if ${COMPILER_VERSION} < 30500
39 # XXX: clang < 3.5 integrated-as doesn't grok .codeNN directives
40 CLANG_NO_IAS34= -no-integrated-as
44 .if ${COMPILER_TYPE} == "gcc"
45 .if ${COMPILER_VERSION} >= 40300
46 # Catch-all for all the things that are in our tree, but for which we're
47 # not yet ready for this compiler. Note: we likely only really "support"
48 # building with gcc 4.8 and newer. Nothing older has been tested.
49 CWARNEXTRA?= -Wno-error=inline -Wno-error=enum-compare -Wno-error=unused-but-set-variable \
50 -Wno-error=aggressive-loop-optimizations -Wno-error=maybe-uninitialized \
51 -Wno-error=array-bounds -Wno-error=address \
52 -Wno-error=cast-qual -Wno-error=sequence-point -Wno-error=attributes \
53 -Wno-error=strict-overflow -Wno-error=overflow
55 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
56 CWARNEXTRA?= -Wno-uninitialized
60 # External compilers may not support our format extensions. Allow them
61 # to be disabled. WARNING: format checking is disabled in this case.
62 .if ${MK_FORMAT_EXTENSIONS} == "no"
63 FORMAT_EXTENSIONS= -Wno-format
64 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
65 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
67 FORMAT_EXTENSIONS= -fformat-extensions
71 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
72 # and above adds code to the entry and exit point of every function to align the
73 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
74 # per function call. While the 16-byte alignment may benefit micro benchmarks,
75 # it is probably an overall loss as it makes the code bigger (less efficient
76 # use of code cache tag lines) and uses more stack (less efficient use of data
77 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
78 # operations inside the kernel itself. These operations are exclusively
79 # reserved for user applications.
82 # Setting -mno-mmx implies -mno-3dnow
83 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
86 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
87 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
89 .if ${MACHINE_CPUARCH} == "i386"
90 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
91 CFLAGS.clang+= -mno-aes -mno-avx
92 CFLAGS+= -mno-mmx -mno-sse -msoft-float
96 .if ${MACHINE_CPUARCH} == "arm"
100 .if ${MACHINE_CPUARCH} == "aarch64"
101 # We generally don't want fpu instructions in the kernel.
102 CFLAGS += -mgeneral-regs-only
103 # Reserve x18 for pcpu data
104 CFLAGS += -ffixed-x18
107 .if ${MACHINE_CPUARCH} == "riscv"
108 CFLAGS.gcc+= -mcmodel=medany
113 # For sparc64 we want the medany code model so modules may be located
114 # anywhere in the 64-bit address space. We also tell GCC to use floating
115 # point emulation. This avoids using floating point registers for integer
116 # operations which it has a tendency to do.
118 .if ${MACHINE_CPUARCH} == "sparc64"
119 CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
120 CFLAGS.gcc+= -mcmodel=medany -msoft-float
125 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
126 # operations inside the kernel itself. These operations are exclusively
127 # reserved for user applications.
130 # Setting -mno-mmx implies -mno-3dnow
131 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
134 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
135 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
136 # (-mfpmath= is not supported)
138 .if ${MACHINE_CPUARCH} == "amd64"
139 CFLAGS.clang+= -mno-aes -mno-avx
140 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
141 -fno-asynchronous-unwind-tables
146 # For PowerPC we tell gcc to use floating point emulation. This avoids using
147 # floating point registers for integer operations which it has a tendency to do.
148 # Also explicitly disable Altivec instructions inside the kernel.
150 .if ${MACHINE_CPUARCH} == "powerpc"
151 CFLAGS+= -mno-altivec
152 CFLAGS.clang+= -mllvm -disable-ppc-float-in-variadic=true
153 CFLAGS.gcc+= -msoft-float
158 # Use dot symbols on powerpc64 to make ddb happy
160 .if ${MACHINE_ARCH} == "powerpc64"
161 CFLAGS.gcc+= -mcall-aixdesc
165 # For MIPS we also tell gcc to use floating point emulation
167 .if ${MACHINE_CPUARCH} == "mips"
168 CFLAGS+= -msoft-float
173 # GCC 3.0 and above like to do certain optimizations based on the
174 # assumption that the program is linked against libc. Stop this.
176 CFLAGS+= -ffreestanding
179 # The C standard leaves signed integer overflow behavior undefined.
180 # gcc and clang opimizers take advantage of this. The kernel makes
181 # use of signed integer wraparound mechanics so we need the compiler
182 # to treat it as a wraparound and not take shortcuts.
189 .if ${MK_SSP} != "no" && \
190 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
191 CFLAGS+= -fstack-protector
195 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
196 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
197 # cope well with DWARF 4, so force it to genereate DWARF2, which they
198 # understand. Do this unconditionally as it is harmless when not needed,
199 # but critical for these newer versions.
201 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
205 CFLAGS+= ${CWARNFLAGS} ${CWARNFLAGS.${.IMPSRC:T}}
206 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
208 # Tell bmake not to mistake standard targets for things to be searched for
209 # or expect to ever be up-to-date.
210 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
211 beforelinking build build-tools buildfiles buildincludes \
212 checkdpadd clean cleandepend cleandir cleanobj configure \
213 depend distclean distribute exe \
214 html includes install installfiles installincludes lint \
215 obj objlink objs objwarn \
216 realinstall regress \
219 .PHONY: ${PHONY_NOTMAIN}
220 .NOTMAIN: ${PHONY_NOTMAIN}
225 CFLAGS+= -traditional
226 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
227 CFLAGS+= -std=iso9899:1990
228 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
229 CFLAGS+= -std=iso9899:199409
230 .elif ${CSTD} == "c99"
231 CFLAGS+= -std=iso9899:1999
233 CFLAGS+= -std=${CSTD}