xref: /freebsd/sys/conf/kern.mk (revision ad30f8e79bd1007cc2476e491bd21b4f5e389e0a)
1# $FreeBSD$
2
3#
4# Warning flags for compiling the kernel and components of the kernel.
5#
6# Note that the newly added -Wcast-qual is responsible for generating
7# most of the remaining warnings.  Warnings introduced with -Wall will
8# also pop up, but are easier to fix.
9.if ${CC:T:Micc} == "icc"
10#CWARNFLAGS=	-w2	# use this if you are terribly bored
11CWARNFLAGS=
12.else
13CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
14		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
15		-Wundef -Wno-pointer-sign -fformat-extensions
16.endif
17#
18# The following flags are next up for working on:
19#	-W
20
21#
22# On the i386, do not align the stack to 16-byte boundaries.  Otherwise GCC
23# 2.95 adds code to the entry and exit point of every function to align the
24# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
25# per function call.  While the 16-byte alignment may benefit micro benchmarks,
26# it is probably an overall loss as it makes the code bigger (less efficient
27# use of code cache tag lines) and uses more stack (less efficient use of data
28# cache tag lines).  Explicitly prohibit the use of SSE and other SIMD
29# operations inside the kernel itself.  These operations are exclusively
30# reserved for user applications.
31#
32.if ${MACHINE_CPUARCH} == "i386" && ${CC:T:Micc} != "icc"
33.if ${CC:T:Mclang} != "clang"
34CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
35.endif
36CFLAGS+=	-mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3 -msoft-float
37INLINE_LIMIT?=	8000
38.endif
39
40.if ${MACHINE_CPUARCH} == "arm"
41INLINE_LIMIT?=	8000
42.endif
43#
44# For IA-64, we use r13 for the kernel globals pointer and we only use
45# a very small subset of float registers for integer divides.
46#
47.if ${MACHINE_CPUARCH} == "ia64"
48CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
49INLINE_LIMIT?=	15000
50.endif
51
52#
53# For sparc64 we want medlow code model, and we tell gcc to use floating
54# point emulation.  This avoids using floating point registers for integer
55# operations which it has a tendency to do.
56#
57.if ${MACHINE_CPUARCH} == "sparc64"
58CFLAGS+=	-mcmodel=medany -msoft-float
59INLINE_LIMIT?=	15000
60.endif
61
62#
63# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
64# operations inside the kernel itself.  These operations are exclusively
65# reserved for user applications.
66#
67.if ${MACHINE_CPUARCH} == "amd64"
68CFLAGS+=	-mcmodel=kernel -mno-red-zone \
69		-mfpmath=387 -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3 \
70		-msoft-float -fno-asynchronous-unwind-tables
71INLINE_LIMIT?=	8000
72.endif
73
74#
75# For PowerPC we tell gcc to use floating point emulation.  This avoids using
76# floating point registers for integer operations which it has a tendency to do.
77# Also explicitly disable Altivec instructions inside the kernel.
78#
79.if ${MACHINE_CPUARCH} == "powerpc"
80CFLAGS+=	-msoft-float -mno-altivec
81INLINE_LIMIT?=	15000
82.endif
83
84#
85# Use dot symbols on powerpc64 to make ddb happy
86#
87.if ${MACHINE_ARCH} == "powerpc64"
88CFLAGS+=	-mcall-aixdesc
89.endif
90
91#
92# For MIPS we also tell gcc to use floating point emulation
93#
94.if ${MACHINE_CPUARCH} == "mips"
95CFLAGS+=	-msoft-float
96INLINE_LIMIT?=	8000
97.endif
98
99#
100# GCC 3.0 and above like to do certain optimizations based on the
101# assumption that the program is linked against libc.  Stop this.
102#
103.if ${CC:T:Micc} == "icc"
104CFLAGS+=	-nolib_inline
105.else
106CFLAGS+=	-ffreestanding
107.endif
108
109.if ${CC:T:Micc} == "icc"
110CFLAGS+=	-restrict
111.endif
112
113#
114# GCC SSP support.
115#
116.if ${MK_SSP} != "no" && ${CC:T:Micc} != "icc" && \
117    ${MACHINE_CPUARCH} != "ia64" && ${MACHINE_CPUARCH} != "arm" && \
118    ${MACHINE_CPUARCH} != "mips"
119CFLAGS+=	-fstack-protector
120.endif
121
122#
123# Enable CTF conversation on request.
124#
125.if defined(WITH_CTF)
126.undef NO_CTF
127.endif
128
129