FreeBSD/Linux Kernel Cross Reference
sys/conf/kern.mk
1 # $FreeBSD: releng/11.2/sys/conf/kern.mk 332306 2018-04-08 20:54:13Z emaste $
2
3 #
4 # Warning flags for compiling the kernel and components of the kernel:
5 #
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 \
11 ${CWARNEXTRA}
12 #
13 # The following flags are next up for working on:
14 # -Wextra
15
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
18 # a false positive.
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
35 .endif
36 .if ${COMPILER_VERSION} >= 40000
37 CWARNEXTRA+= -Wno-error-address-of-packed-member
38 .endif
39
40 CLANG_NO_IAS= -no-integrated-as
41 .if ${COMPILER_VERSION} < 30500
42 # XXX: clang < 3.5 integrated-as doesn't grok .codeNN directives
43 CLANG_NO_IAS34= -no-integrated-as
44 .endif
45 .endif
46
47 .if ${COMPILER_TYPE} == "gcc"
48 .if ${COMPILER_VERSION} >= 40800
49 # Catch-all for all the things that are in our tree, but for which we're
50 # not yet ready for this compiler.
51 CWARNEXTRA?= -Wno-error=address \
52 -Wno-error=aggressive-loop-optimizations \
53 -Wno-error=array-bounds \
54 -Wno-error=attributes \
55 -Wno-error=cast-qual \
56 -Wno-error=enum-compare \
57 -Wno-error=inline \
58 -Wno-error=maybe-uninitialized \
59 -Wno-error=overflow \
60 -Wno-error=sequence-point \
61 -Wno-error=unused-but-set-variable
62 .if ${COMPILER_VERSION} >= 60100
63 CWARNEXTRA+= -Wno-error=misleading-indentation \
64 -Wno-error=nonnull-compare \
65 -Wno-error=shift-overflow \
66 -Wno-error=tautological-compare
67 .endif
68 .else
69 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
70 CWARNEXTRA?= -Wno-uninitialized
71 .endif
72 .endif
73
74 # External compilers may not support our format extensions. Allow them
75 # to be disabled. WARNING: format checking is disabled in this case.
76 .if ${MK_FORMAT_EXTENSIONS} == "no"
77 FORMAT_EXTENSIONS= -Wno-format
78 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
79 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
80 .else
81 FORMAT_EXTENSIONS= -fformat-extensions
82 .endif
83
84 #
85 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
86 # and above adds code to the entry and exit point of every function to align the
87 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
88 # per function call. While the 16-byte alignment may benefit micro benchmarks,
89 # it is probably an overall loss as it makes the code bigger (less efficient
90 # use of code cache tag lines) and uses more stack (less efficient use of data
91 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
92 # operations inside the kernel itself. These operations are exclusively
93 # reserved for user applications.
94 #
95 # gcc:
96 # Setting -mno-mmx implies -mno-3dnow
97 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
98 #
99 # clang:
100 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
101 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
102 #
103 .if ${MACHINE_CPUARCH} == "i386"
104 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
105 CFLAGS.clang+= -mno-aes -mno-avx
106 CFLAGS+= -mno-mmx -mno-sse -msoft-float
107 INLINE_LIMIT?= 8000
108 .endif
109
110 .if ${MACHINE_CPUARCH} == "arm"
111 INLINE_LIMIT?= 8000
112 .endif
113
114 .if ${MACHINE_CPUARCH} == "aarch64"
115 # We generally don't want fpu instructions in the kernel.
116 CFLAGS += -mgeneral-regs-only
117 # Reserve x18 for pcpu data
118 CFLAGS += -ffixed-x18
119 .endif
120
121 .if ${MACHINE_CPUARCH} == "riscv"
122 CFLAGS.gcc+= -mcmodel=medany
123 INLINE_LIMIT?= 8000
124 .endif
125
126 #
127 # For sparc64 we want the medany code model so modules may be located
128 # anywhere in the 64-bit address space. We also tell GCC to use floating
129 # point emulation. This avoids using floating point registers for integer
130 # operations which it has a tendency to do.
131 #
132 .if ${MACHINE_CPUARCH} == "sparc64"
133 CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
134 CFLAGS.gcc+= -mcmodel=medany -msoft-float
135 INLINE_LIMIT?= 15000
136 .endif
137
138 #
139 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
140 # operations inside the kernel itself. These operations are exclusively
141 # reserved for user applications.
142 #
143 # gcc:
144 # Setting -mno-mmx implies -mno-3dnow
145 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
146 #
147 # clang:
148 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
149 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
150 # (-mfpmath= is not supported)
151 #
152 .if ${MACHINE_CPUARCH} == "amd64"
153 CFLAGS.clang+= -mno-aes -mno-avx
154 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
155 -fno-asynchronous-unwind-tables
156 INLINE_LIMIT?= 8000
157 .endif
158
159 #
160 # For PowerPC we tell gcc to use floating point emulation. This avoids using
161 # floating point registers for integer operations which it has a tendency to do.
162 # Also explicitly disable Altivec instructions inside the kernel.
163 #
164 .if ${MACHINE_CPUARCH} == "powerpc"
165 CFLAGS+= -mno-altivec -msoft-float
166 INLINE_LIMIT?= 15000
167 .endif
168
169 #
170 # Use dot symbols on powerpc64 to make ddb happy
171 #
172 .if ${MACHINE_ARCH} == "powerpc64"
173 CFLAGS.gcc+= -mcall-aixdesc
174 .endif
175
176 #
177 # For MIPS we also tell gcc to use floating point emulation
178 #
179 .if ${MACHINE_CPUARCH} == "mips"
180 CFLAGS+= -msoft-float
181 INLINE_LIMIT?= 8000
182 .endif
183
184 #
185 # GCC 3.0 and above like to do certain optimizations based on the
186 # assumption that the program is linked against libc. Stop this.
187 #
188 CFLAGS+= -ffreestanding
189
190 #
191 # The C standard leaves signed integer overflow behavior undefined.
192 # gcc and clang opimizers take advantage of this. The kernel makes
193 # use of signed integer wraparound mechanics so we need the compiler
194 # to treat it as a wraparound and not take shortcuts.
195 #
196 CFLAGS+= -fwrapv
197
198 #
199 # GCC SSP support
200 #
201 .if ${MK_SSP} != "no" && \
202 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
203 CFLAGS+= -fstack-protector
204 .endif
205
206 #
207 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
208 #
209 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
210 ${MK_KERNEL_RETPOLINE} != "no"
211 CFLAGS+= -mretpoline
212 .endif
213
214 #
215 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
216 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
217 # cope well with DWARF 4, so force it to genereate DWARF2, which they
218 # understand. Do this unconditionally as it is harmless when not needed,
219 # but critical for these newer versions.
220 #
221 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
222 CFLAGS+= -gdwarf-2
223 .endif
224
225 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
226 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
227
228 # Tell bmake not to mistake standard targets for things to be searched for
229 # or expect to ever be up-to-date.
230 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
231 beforelinking build build-tools buildfiles buildincludes \
232 checkdpadd clean cleandepend cleandir cleanobj configure \
233 depend distclean distribute exe \
234 html includes install installfiles installincludes lint \
235 obj objlink objs objwarn \
236 realinstall regress \
237 tags whereobj
238
239 .PHONY: ${PHONY_NOTMAIN}
240 .NOTMAIN: ${PHONY_NOTMAIN}
241
242 CSTD= c99
243
244 .if ${CSTD} == "k&r"
245 CFLAGS+= -traditional
246 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
247 CFLAGS+= -std=iso9899:1990
248 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
249 CFLAGS+= -std=iso9899:199409
250 .elif ${CSTD} == "c99"
251 CFLAGS+= -std=iso9899:1999
252 .else # CSTD
253 CFLAGS+= -std=${CSTD}
254 .endif # CSTD
255
256 # Set target-specific linker emulation name. Used by ld -b binary to convert
257 # binary files into ELF objects.
258 LD_EMULATION_aarch64=aarch64elf
259 LD_EMULATION_amd64=elf_x86_64_fbsd
260 LD_EMULATION_arm=armelf_fbsd
261 LD_EMULATION_armeb=armelfb_fbsd
262 LD_EMULATION_armv6=armelf_fbsd
263 LD_EMULATION_i386=elf_i386_fbsd
264 LD_EMULATION_mips= elf32btsmip_fbsd
265 LD_EMULATION_mips64= elf64btsmip_fbsd
266 LD_EMULATION_mipsel= elf32ltsmip_fbsd
267 LD_EMULATION_mips64el= elf64ltsmip_fbsd
268 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
269 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
270 LD_EMULATION_powerpc= elf32ppc_fbsd
271 LD_EMULATION_powerpc64= elf64ppc_fbsd
272 LD_EMULATION_riscv64= elf64lriscv
273 LD_EMULATION_sparc64= elf64_sparc_fbsd
274 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}
Cache object: 5c71387fbbb2c1989b48b0876e45b4bb
|