xref: /freebsd/sys/conf/kern.mk (revision 9fd69f37d28cfd7438cac3eeb45fe9dd46b4d7dd)
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.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_ARCH} == "i386" && ${CC} != "icc"
33CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2 \
34		-mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3
35INLINE_LIMIT?=	8000
36.endif
37
38.if ${MACHINE_ARCH} == "arm"
39INLINE_LIMIT?=	8000
40.endif
41#
42# For IA-64, we use r13 for the kernel globals pointer and we only use
43# a very small subset of float registers for integer divides.
44#
45.if ${MACHINE_ARCH} == "ia64"
46CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
47INLINE_LIMIT?=	15000
48.endif
49
50#
51# For sparc64 we want medlow code model, and we tell gcc to use floating
52# point emulation.  This avoids using floating point registers for integer
53# operations which it has a tendency to do.
54#
55.if ${MACHINE_ARCH} == "sparc64"
56CFLAGS+=	-mcmodel=medany -msoft-float
57INLINE_LIMIT?=	15000
58.endif
59
60#
61# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
62# operations inside the kernel itself.  These operations are exclusively
63# reserved for user applications.
64#
65.if ${MACHINE_ARCH} == "amd64"
66CFLAGS+=	-mcmodel=kernel -mno-red-zone \
67		-mfpmath=387 -mno-sse -mno-sse2 -mno-sse3 -mno-mmx -mno-3dnow \
68		-msoft-float -fno-asynchronous-unwind-tables
69INLINE_LIMIT?=	8000
70.endif
71
72#
73# For PowerPC we tell gcc to use floating point emulation.  This avoids using
74# floating point registers for integer operations which it has a tendency to do.
75# Also explicitly disable Altivec instructions inside the kernel.
76#
77.if ${MACHINE_ARCH} == "powerpc"
78CFLAGS+=	-msoft-float -mno-altivec
79INLINE_LIMIT?=	15000
80.endif
81
82#
83# For MIPS we also tell gcc to use floating point emulation
84#
85.if ${MACHINE_ARCH} == "mips"
86CFLAGS+=	-msoft-float
87INLINE_LIMIT?=	8000
88.endif
89
90#
91# GCC 3.0 and above like to do certain optimizations based on the
92# assumption that the program is linked against libc.  Stop this.
93#
94.if ${CC} == "icc"
95CFLAGS+=	-nolib_inline
96.else
97CFLAGS+=	-ffreestanding
98.endif
99
100.if ${CC} == "icc"
101CFLAGS+=	-restrict
102.endif
103
104#
105# GCC SSP support.
106#
107.if ${MK_SSP} != "no" && ${CC} != "icc" && ${MACHINE_ARCH} != "ia64" && \
108	${MACHINE_ARCH} != "arm" && ${MACHINE_ARCH} != "mips"
109CFLAGS+=	-fstack-protector
110.endif
111