FreeBSD/Linux Kernel Cross Reference
sys/conf/kern.mk
1 # $FreeBSD: src/sys/conf/kern.mk,v 1.57 2008/07/23 06:16:34 imp Exp $
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
11 CWARNFLAGS=
12 .else
13 CWARNFLAGS?= -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"
39 CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2 \
40 -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3
41 INLINE_LIMIT?= 8000
42 .endif
43
44 .if ${MACHINE_ARCH} == "arm"
45 INLINE_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"
52 CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
53 INLINE_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"
62 CFLAGS+= -mcmodel=medany -msoft-float
63 INLINE_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"
72 CFLAGS+= -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
75 INLINE_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"
83 CFLAGS+= -msoft-float
84 INLINE_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"
92 CFLAGS+= -msoft-float -mno-dsp
93 INLINE_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"
101 CFLAGS+= -nolib_inline
102 .else
103 CFLAGS+= -ffreestanding
104 .endif
105
106 .if ${CC} == "icc"
107 CFLAGS+= -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"
115 CFLAGS+= -fstack-protector
116 .endif
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