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} >= 40800
46 # Catch-all for all the things that are in our tree, but for which we're
47 # not yet ready for this compiler.
48 CWARNEXTRA?= -Wno-error=inline -Wno-error=enum-compare -Wno-error=unused-but-set-variable \
49 -Wno-error=aggressive-loop-optimizations -Wno-error=maybe-uninitialized \
50 -Wno-error=array-bounds -Wno-error=address \
51 -Wno-error=cast-qual -Wno-error=sequence-point -Wno-error=attributes \
52 -Wno-error=strict-overflow -Wno-error=overflow
54 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
55 CWARNEXTRA?= -Wno-uninitialized
59 # External compilers may not support our format extensions. Allow them
60 # to be disabled. WARNING: format checking is disabled in this case.
61 .if ${MK_FORMAT_EXTENSIONS} == "no"
62 FORMAT_EXTENSIONS= -Wno-format
63 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
64 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
66 FORMAT_EXTENSIONS= -fformat-extensions
70 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
71 # and above adds code to the entry and exit point of every function to align the
72 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
73 # per function call. While the 16-byte alignment may benefit micro benchmarks,
74 # it is probably an overall loss as it makes the code bigger (less efficient
75 # use of code cache tag lines) and uses more stack (less efficient use of data
76 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
77 # operations inside the kernel itself. These operations are exclusively
78 # reserved for user applications.
81 # Setting -mno-mmx implies -mno-3dnow
82 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
85 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
86 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
88 .if ${MACHINE_CPUARCH} == "i386"
89 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
90 CFLAGS.clang+= -mno-aes -mno-avx
91 CFLAGS+= -mno-mmx -mno-sse -msoft-float
95 .if ${MACHINE_CPUARCH} == "arm"
99 .if ${MACHINE_CPUARCH} == "aarch64"
100 # We generally don't want fpu instructions in the kernel.
101 CFLAGS += -mgeneral-regs-only
102 # Reserve x18 for pcpu data
103 CFLAGS += -ffixed-x18
106 .if ${MACHINE_CPUARCH} == "riscv"
107 CFLAGS.gcc+= -mcmodel=medany
112 # For sparc64 we want the medany code model so modules may be located
113 # anywhere in the 64-bit address space. We also tell GCC to use floating
114 # point emulation. This avoids using floating point registers for integer
115 # operations which it has a tendency to do.
117 .if ${MACHINE_CPUARCH} == "sparc64"
118 CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
119 CFLAGS.gcc+= -mcmodel=medany -msoft-float
124 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
125 # operations inside the kernel itself. These operations are exclusively
126 # reserved for user applications.
129 # Setting -mno-mmx implies -mno-3dnow
130 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
133 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
134 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
135 # (-mfpmath= is not supported)
137 .if ${MACHINE_CPUARCH} == "amd64"
138 CFLAGS.clang+= -mno-aes -mno-avx
139 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
140 -fno-asynchronous-unwind-tables
145 # For PowerPC we tell gcc to use floating point emulation. This avoids using
146 # floating point registers for integer operations which it has a tendency to do.
147 # Also explicitly disable Altivec instructions inside the kernel.
149 .if ${MACHINE_CPUARCH} == "powerpc"
150 CFLAGS+= -mno-altivec
151 CFLAGS.clang+= -mllvm -disable-ppc-float-in-variadic=true
152 CFLAGS.gcc+= -msoft-float
157 # Use dot symbols on powerpc64 to make ddb happy
159 .if ${MACHINE_ARCH} == "powerpc64"
160 CFLAGS.gcc+= -mcall-aixdesc
164 # For MIPS we also tell gcc to use floating point emulation
166 .if ${MACHINE_CPUARCH} == "mips"
167 CFLAGS+= -msoft-float
172 # GCC 3.0 and above like to do certain optimizations based on the
173 # assumption that the program is linked against libc. Stop this.
175 CFLAGS+= -ffreestanding
178 # The C standard leaves signed integer overflow behavior undefined.
179 # gcc and clang opimizers take advantage of this. The kernel makes
180 # use of signed integer wraparound mechanics so we need the compiler
181 # to treat it as a wraparound and not take shortcuts.
188 .if ${MK_SSP} != "no" && \
189 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
190 CFLAGS+= -fstack-protector
194 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
195 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
196 # cope well with DWARF 4, so force it to genereate DWARF2, which they
197 # understand. Do this unconditionally as it is harmless when not needed,
198 # but critical for these newer versions.
200 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
204 CFLAGS+= ${CWARNFLAGS} ${CWARNFLAGS.${.IMPSRC:T}}
205 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
207 # Tell bmake not to mistake standard targets for things to be searched for
208 # or expect to ever be up-to-date.
209 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
210 beforelinking build build-tools buildfiles buildincludes \
211 checkdpadd clean cleandepend cleandir cleanobj configure \
212 depend distclean distribute exe \
213 html includes install installfiles installincludes lint \
214 obj objlink objs objwarn \
215 realinstall regress \
218 .PHONY: ${PHONY_NOTMAIN}
219 .NOTMAIN: ${PHONY_NOTMAIN}
224 CFLAGS+= -traditional
225 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
226 CFLAGS+= -std=iso9899:1990
227 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
228 CFLAGS+= -std=iso9899:199409
229 .elif ${CSTD} == "c99"
230 CFLAGS+= -std=iso9899:1999
232 CFLAGS+= -std=${CSTD}