FreeBSD/Linux Kernel Cross Reference
sys/conf/kern.mk
1 # $FreeBSD: releng/11.1/sys/conf/kern.mk 318170 2017-05-11 03:41:55Z jhb $
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=inline -Wno-error=enum-compare -Wno-error=unused-but-set-variable \
52 -Wno-error=aggressive-loop-optimizations -Wno-error=maybe-uninitialized \
53 -Wno-error=array-bounds -Wno-error=address \
54 -Wno-error=cast-qual -Wno-error=sequence-point -Wno-error=attributes \
55 -Wno-error=strict-overflow -Wno-error=overflow
56 .else
57 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
58 CWARNEXTRA?= -Wno-uninitialized
59 .endif
60 .endif
61
62 # External compilers may not support our format extensions. Allow them
63 # to be disabled. WARNING: format checking is disabled in this case.
64 .if ${MK_FORMAT_EXTENSIONS} == "no"
65 FORMAT_EXTENSIONS= -Wno-format
66 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
67 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
68 .else
69 FORMAT_EXTENSIONS= -fformat-extensions
70 .endif
71
72 #
73 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
74 # and above adds code to the entry and exit point of every function to align the
75 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
76 # per function call. While the 16-byte alignment may benefit micro benchmarks,
77 # it is probably an overall loss as it makes the code bigger (less efficient
78 # use of code cache tag lines) and uses more stack (less efficient use of data
79 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
80 # operations inside the kernel itself. These operations are exclusively
81 # reserved for user applications.
82 #
83 # gcc:
84 # Setting -mno-mmx implies -mno-3dnow
85 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
86 #
87 # clang:
88 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
89 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
90 #
91 .if ${MACHINE_CPUARCH} == "i386"
92 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
93 CFLAGS.clang+= -mno-aes -mno-avx
94 CFLAGS+= -mno-mmx -mno-sse -msoft-float
95 INLINE_LIMIT?= 8000
96 .endif
97
98 .if ${MACHINE_CPUARCH} == "arm"
99 INLINE_LIMIT?= 8000
100 .endif
101
102 .if ${MACHINE_CPUARCH} == "aarch64"
103 # We generally don't want fpu instructions in the kernel.
104 CFLAGS += -mgeneral-regs-only
105 # Reserve x18 for pcpu data
106 CFLAGS += -ffixed-x18
107 .endif
108
109 .if ${MACHINE_CPUARCH} == "riscv"
110 CFLAGS.gcc+= -mcmodel=medany
111 INLINE_LIMIT?= 8000
112 .endif
113
114 #
115 # For sparc64 we want the medany code model so modules may be located
116 # anywhere in the 64-bit address space. We also tell GCC to use floating
117 # point emulation. This avoids using floating point registers for integer
118 # operations which it has a tendency to do.
119 #
120 .if ${MACHINE_CPUARCH} == "sparc64"
121 CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
122 CFLAGS.gcc+= -mcmodel=medany -msoft-float
123 INLINE_LIMIT?= 15000
124 .endif
125
126 #
127 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
128 # operations inside the kernel itself. These operations are exclusively
129 # reserved for user applications.
130 #
131 # gcc:
132 # Setting -mno-mmx implies -mno-3dnow
133 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
134 #
135 # clang:
136 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
137 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
138 # (-mfpmath= is not supported)
139 #
140 .if ${MACHINE_CPUARCH} == "amd64"
141 CFLAGS.clang+= -mno-aes -mno-avx
142 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
143 -fno-asynchronous-unwind-tables
144 INLINE_LIMIT?= 8000
145 .endif
146
147 #
148 # For PowerPC we tell gcc to use floating point emulation. This avoids using
149 # floating point registers for integer operations which it has a tendency to do.
150 # Also explicitly disable Altivec instructions inside the kernel.
151 #
152 .if ${MACHINE_CPUARCH} == "powerpc"
153 CFLAGS+= -mno-altivec -msoft-float
154 INLINE_LIMIT?= 15000
155 .endif
156
157 #
158 # Use dot symbols on powerpc64 to make ddb happy
159 #
160 .if ${MACHINE_ARCH} == "powerpc64"
161 CFLAGS.gcc+= -mcall-aixdesc
162 .endif
163
164 #
165 # For MIPS we also tell gcc to use floating point emulation
166 #
167 .if ${MACHINE_CPUARCH} == "mips"
168 CFLAGS+= -msoft-float
169 INLINE_LIMIT?= 8000
170 .endif
171
172 #
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.
175 #
176 CFLAGS+= -ffreestanding
177
178 #
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.
183 #
184 CFLAGS+= -fwrapv
185
186 #
187 # GCC SSP support
188 #
189 .if ${MK_SSP} != "no" && \
190 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
191 CFLAGS+= -fstack-protector
192 .endif
193
194 #
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.
200 #
201 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
202 CFLAGS+= -gdwarf-2
203 .endif
204
205 CFLAGS+= ${CWARNFLAGS} ${CWARNFLAGS.${.IMPSRC:T}}
206 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
207
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 \
217 tags whereobj
218
219 .PHONY: ${PHONY_NOTMAIN}
220 .NOTMAIN: ${PHONY_NOTMAIN}
221
222 CSTD= c99
223
224 .if ${CSTD} == "k&r"
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 ${CSTD} == "c99"
231 CFLAGS+= -std=iso9899:1999
232 .else # CSTD
233 CFLAGS+= -std=${CSTD}
234 .endif # CSTD
235
236 # Set target-specific linker emulation name. Used by ld -b binary to convert
237 # binary files into ELF objects.
238 LD_EMULATION_aarch64=aarch64elf
239 LD_EMULATION_amd64=elf_x86_64_fbsd
240 LD_EMULATION_arm=armelf_fbsd
241 LD_EMULATION_armeb=armelfb_fbsd
242 LD_EMULATION_armv6=armelf_fbsd
243 LD_EMULATION_i386=elf_i386_fbsd
244 LD_EMULATION_mips= elf32btsmip_fbsd
245 LD_EMULATION_mips64= elf64btsmip_fbsd
246 LD_EMULATION_mipsel= elf32ltsmip_fbsd
247 LD_EMULATION_mips64el= elf64ltsmip_fbsd
248 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
249 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
250 LD_EMULATION_powerpc= elf32ppc_fbsd
251 LD_EMULATION_powerpc64= elf64ppc_fbsd
252 LD_EMULATION_riscv64= elf64lriscv
253 LD_EMULATION_sparc64= elf64_sparc_fbsd
254 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}
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