xref: /freebsd/sys/conf/kern.mk (revision cc3f4b99653c34ae64f8a1fddea370abefef680e)
1# $FreeBSD$
2
3# Compat
4MK_FORMAT_EXTENSIONS?=no
5
6#
7# Warning flags for compiling the kernel and components of the kernel:
8#
9CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
10		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
11		-Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
12		-Wmissing-include-dirs -fdiagnostics-show-option \
13		${CWARNEXTRA}
14#
15# The following flags are next up for working on:
16#	-Wextra
17
18# Disable a few warnings for clang, since there are several places in the
19# kernel where fixing them is more trouble than it is worth, or where there is
20# a false positive.
21.if ${COMPILER_TYPE} == "clang"
22NO_WCONSTANT_CONVERSION=	-Wno-constant-conversion
23NO_WARRAY_BOUNDS=		-Wno-array-bounds
24NO_WSHIFT_COUNT_NEGATIVE=	-Wno-shift-count-negative
25NO_WSHIFT_COUNT_OVERFLOW=	-Wno-shift-count-overflow
26NO_WUNUSED_VALUE=		-Wno-unused-value
27NO_WSELF_ASSIGN=		-Wno-self-assign
28NO_WFORMAT_SECURITY=		-Wno-format-security
29NO_WUNNEEDED_INTERNAL_DECL=	-Wno-unneeded-internal-declaration
30NO_WSOMETIMES_UNINITIALIZED=	-Wno-error-sometimes-uninitialized
31# Several other warnings which might be useful in some cases, but not severe
32# enough to error out the whole kernel build.  Display them anyway, so there is
33# some incentive to fix them eventually.
34CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
35		-Wno-error-parentheses-equality -Wno-unused-function \
36		${NO_WFORMAT}
37.endif
38
39# External compilers may not support our format extensions.  Allow them
40# to be disabled.  WARNING: format checking is disabled in this case.
41.if ${MK_FORMAT_EXTENSIONS} == "no"
42NO_WFORMAT=		-Wno-format
43.else
44FORMAT_EXTENSIONS=	-fformat-extensions
45.endif
46
47#
48# On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
49# and above adds code to the entry and exit point of every function to align the
50# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
51# per function call.  While the 16-byte alignment may benefit micro benchmarks,
52# it is probably an overall loss as it makes the code bigger (less efficient
53# use of code cache tag lines) and uses more stack (less efficient use of data
54# cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
55# operations inside the kernel itself.  These operations are exclusively
56# reserved for user applications.
57#
58# gcc:
59# Setting -mno-mmx implies -mno-3dnow
60# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
61#
62# clang:
63# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
64# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
65#
66.if ${MACHINE_CPUARCH} == "i386"
67.if ${COMPILER_TYPE} != "clang"
68CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
69.else
70CFLAGS+=	-mno-aes -mno-avx
71.endif
72CFLAGS+=	-mno-mmx -mno-sse -msoft-float
73INLINE_LIMIT?=	8000
74.endif
75
76.if ${MACHINE_CPUARCH} == "arm"
77INLINE_LIMIT?=	8000
78.endif
79
80#
81# For IA-64, we use r13 for the kernel globals pointer and we only use
82# a very small subset of float registers for integer divides.
83#
84.if ${MACHINE_CPUARCH} == "ia64"
85CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
86INLINE_LIMIT?=	15000
87.endif
88
89#
90# For sparc64 we want the medany code model so modules may be located
91# anywhere in the 64-bit address space.  We also tell GCC to use floating
92# point emulation.  This avoids using floating point registers for integer
93# operations which it has a tendency to do.
94#
95.if ${MACHINE_CPUARCH} == "sparc64"
96.if ${COMPILER_TYPE} == "clang"
97CFLAGS+=	-mcmodel=large -fno-dwarf2-cfi-asm
98.else
99CFLAGS+=	-mcmodel=medany -msoft-float
100.endif
101INLINE_LIMIT?=	15000
102.endif
103
104#
105# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
106# operations inside the kernel itself.  These operations are exclusively
107# reserved for user applications.
108#
109# gcc:
110# Setting -mno-mmx implies -mno-3dnow
111# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
112#
113# clang:
114# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
115# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
116# (-mfpmath= is not supported)
117#
118.if ${MACHINE_CPUARCH} == "amd64"
119.if ${COMPILER_TYPE} == "clang"
120CFLAGS+=	-mno-aes -mno-avx
121.endif
122CFLAGS+=	-mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
123		-fno-asynchronous-unwind-tables
124INLINE_LIMIT?=	8000
125.endif
126
127#
128# For PowerPC we tell gcc to use floating point emulation.  This avoids using
129# floating point registers for integer operations which it has a tendency to do.
130# Also explicitly disable Altivec instructions inside the kernel.
131#
132.if ${MACHINE_CPUARCH} == "powerpc"
133CFLAGS+=	-msoft-float -mno-altivec
134INLINE_LIMIT?=	15000
135.endif
136
137#
138# Use dot symbols on powerpc64 to make ddb happy
139#
140.if ${MACHINE_ARCH} == "powerpc64"
141CFLAGS+=	-mcall-aixdesc
142.endif
143
144#
145# For MIPS we also tell gcc to use floating point emulation
146#
147.if ${MACHINE_CPUARCH} == "mips"
148CFLAGS+=	-msoft-float
149INLINE_LIMIT?=	8000
150.endif
151
152#
153# GCC 3.0 and above like to do certain optimizations based on the
154# assumption that the program is linked against libc.  Stop this.
155#
156CFLAGS+=	-ffreestanding
157
158#
159# GCC SSP support
160#
161.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
162    ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
163CFLAGS+=	-fstack-protector
164.endif
165
166#
167# Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
168# and gcc 4.8 is to generate DWARF version 4. However, our tools don't
169# cope well with DWARF 4, so force it to genereate DWARF2, which they
170# understand. Do this unconditionally as it is harmless when not needed,
171# but critical for these newer versions.
172#
173.if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
174CFLAGS+=	-gdwarf-2
175.endif
176