xref: /freebsd/sys/conf/kern.mk (revision 884a2a699669ec61e2366e3e358342dbc94be24a)
1# $FreeBSD$
2
3#
4# Warning flags for compiling the kernel and components of the kernel:
5#
6CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
7		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
8		-Wundef -Wno-pointer-sign -fformat-extensions \
9		-Wmissing-include-dirs -fdiagnostics-show-option
10#
11# The following flags are next up for working on:
12#	-Wextra
13
14#
15# On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
16# and above adds code to the entry and exit point of every function to align the
17# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
18# per function call.  While the 16-byte alignment may benefit micro benchmarks,
19# it is probably an overall loss as it makes the code bigger (less efficient
20# use of code cache tag lines) and uses more stack (less efficient use of data
21# cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
22# operations inside the kernel itself.  These operations are exclusively
23# reserved for user applications.
24#
25# gcc:
26# Setting -mno-mmx implies -mno-3dnow
27# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
28#
29# clang:
30# Setting -mno-mmx implies -mno-3dnow, -mno-3dnowa, -mno-sse, -mno-sse2,
31#                          -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
32#
33.if ${MACHINE_CPUARCH} == "i386"
34.if ${CC:T:Mclang} != "clang"
35CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2 -mno-sse
36.else
37CFLAGS+=	-mno-aes -mno-avx
38.endif
39CFLAGS+=	-mno-mmx -msoft-float
40INLINE_LIMIT?=	8000
41.endif
42
43.if ${MACHINE_CPUARCH} == "arm"
44INLINE_LIMIT?=	8000
45.endif
46
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_CPUARCH} == "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_CPUARCH} == "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# gcc:
72# Setting -mno-mmx implies -mno-3dnow
73# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
74#
75# clang:
76# Setting -mno-mmx implies -mno-3dnow, -mno-3dnowa, -mno-sse, -mno-sse2,
77#                          -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
78# (-mfpmath= is not supported)
79#
80.if ${MACHINE_CPUARCH} == "amd64"
81.if ${CC:T:Mclang} != "clang"
82CFLAGS+=	-mno-sse
83.else
84CFLAGS+=	-mno-aes -mno-avx
85.endif
86CFLAGS+=	-mcmodel=kernel -mno-red-zone -mno-mmx -msoft-float \
87		-fno-asynchronous-unwind-tables
88INLINE_LIMIT?=	8000
89.endif
90
91#
92# For PowerPC we tell gcc to use floating point emulation.  This avoids using
93# floating point registers for integer operations which it has a tendency to do.
94# Also explicitly disable Altivec instructions inside the kernel.
95#
96.if ${MACHINE_CPUARCH} == "powerpc"
97CFLAGS+=	-msoft-float -mno-altivec
98INLINE_LIMIT?=	15000
99.endif
100
101#
102# Use dot symbols on powerpc64 to make ddb happy
103#
104.if ${MACHINE_ARCH} == "powerpc64"
105CFLAGS+=	-mcall-aixdesc
106.endif
107
108#
109# For MIPS we also tell gcc to use floating point emulation
110#
111.if ${MACHINE_CPUARCH} == "mips"
112CFLAGS+=	-msoft-float
113INLINE_LIMIT?=	8000
114.endif
115
116#
117# GCC 3.0 and above like to do certain optimizations based on the
118# assumption that the program is linked against libc.  Stop this.
119#
120CFLAGS+=	-ffreestanding
121
122#
123# GCC SSP support
124#
125.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
126    ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
127CFLAGS+=	-fstack-protector
128.endif
129
130#
131# Enable CTF conversation on request
132#
133.if defined(WITH_CTF)
134.undef NO_CTF
135.endif
136