xref: /freebsd/sys/conf/kern.mk (revision 5c52a79884070364bfc920fb8e492cfac61ec72f)
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} == "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.if !defined(WITH_GCC3)
17_Wno_pointer_sign=-Wno-pointer-sign
18.endif
19.if !defined(NO_UNDEF)
20_wundef=	-Wundef
21.endif
22.endif
23#
24# The following flags are next up for working on:
25#	-W
26
27#
28# On the i386, do not align the stack to 16-byte boundaries.  Otherwise GCC
29# 2.95 adds code to the entry and exit point of every function to align the
30# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
31# per function call.  While the 16-byte alignment may benefit micro benchmarks,
32# it is probably an overall loss as it makes the code bigger (less efficient
33# use of code cache tag lines) and uses more stack (less efficient use of data
34# cache tag lines).  Explicitly prohibit the use of SSE and other SIMD
35# operations inside the kernel itself.  These operations are exclusively
36# reserved for user applications.
37#
38.if ${MACHINE_ARCH} == "i386" && ${CC} != "icc"
39CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2 \
40		-mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3
41INLINE_LIMIT?=	8000
42.endif
43
44.if ${MACHINE_ARCH} == "arm"
45INLINE_LIMIT?=	8000
46.endif
47#
48# For IA-64, we use r13 for the kernel globals pointer and we only use
49# a very small subset of float registers for integer divides.
50#
51.if ${MACHINE_ARCH} == "ia64"
52CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
53INLINE_LIMIT?=	15000
54.endif
55
56#
57# For sparc64 we want medlow code model, and we tell gcc to use floating
58# point emulation.  This avoids using floating point registers for integer
59# operations which it has a tendency to do.
60#
61.if ${MACHINE_ARCH} == "sparc64"
62CFLAGS+=	-mcmodel=medany -msoft-float
63INLINE_LIMIT?=	15000
64.endif
65
66#
67# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
68# operations inside the kernel itself.  These operations are exclusively
69# reserved for user applications.
70#
71.if ${MACHINE_ARCH} == "amd64"
72CFLAGS+=	-mcmodel=kernel -mno-red-zone \
73		-mfpmath=387 -mno-sse -mno-sse2 -mno-sse3 -mno-mmx -mno-3dnow \
74		-msoft-float -fno-asynchronous-unwind-tables
75INLINE_LIMIT?=	8000
76.endif
77
78#
79# For PowerPC we tell gcc to use floating point emulation.  This avoids using
80# floating point registers for integer operations which it has a tendency to do.
81#
82.if ${MACHINE_ARCH} == "powerpc"
83CFLAGS+=	-msoft-float
84INLINE_LIMIT?=	15000
85.endif
86
87#
88# For MIPS we also tell gcc to use floating point emulation and
89# disable MIPS DSP ASE Instruction set.
90#
91.if ${MACHINE_ARCH} == "mips"
92CFLAGS+=	-msoft-float -mno-dsp
93INLINE_LIMIT?=	15000
94.endif
95
96#
97# GCC 3.0 and above like to do certain optimizations based on the
98# assumption that the program is linked against libc.  Stop this.
99#
100.if ${CC} == "icc"
101CFLAGS+=	-nolib_inline
102.else
103CFLAGS+=	-ffreestanding
104.endif
105
106.if ${CC} == "icc"
107CFLAGS+=	-restrict
108.endif
109
110#
111# GCC SSP support.
112#
113.if ${MK_SSP} != "no" && ${CC} != "icc" && ${MACHINE_ARCH} != "ia64" && \
114	${MACHINE_ARCH} != "arm" && ${MACHINE_ARCH} != "mips"
115CFLAGS+=	-fstack-protector
116.endif
117