kern.mk revision 263508 
1# $FreeBSD: stable/10/sys/conf/kern.mk 263508 2014-03-21 17:53:59Z dim $
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 ${FORMAT_EXTENSIONS} \
9		-Wmissing-include-dirs -fdiagnostics-show-option \
10		${CWARNEXTRA}
11#
12# The following flags are next up for working on:
13#	-Wextra
14
15# Disable a few warnings for clang, since there are several places in the
16# kernel where fixing them is more trouble than it is worth, or where there is
17# a false positive.
18.if ${COMPILER_TYPE} == "clang"
19NO_WCONSTANT_CONVERSION=	-Wno-constant-conversion
20NO_WARRAY_BOUNDS=		-Wno-array-bounds
21NO_WSHIFT_COUNT_NEGATIVE=	-Wno-shift-count-negative
22NO_WSHIFT_COUNT_OVERFLOW=	-Wno-shift-count-overflow
23NO_WUNUSED_VALUE=		-Wno-unused-value
24NO_WSELF_ASSIGN=		-Wno-self-assign
25NO_WFORMAT_SECURITY=		-Wno-format-security
26NO_WUNNEEDED_INTERNAL_DECL=	-Wno-unneeded-internal-declaration
27NO_WSOMETIMES_UNINITIALIZED=	-Wno-error-sometimes-uninitialized
28# Several other warnings which might be useful in some cases, but not severe
29# enough to error out the whole kernel build.  Display them anyway, so there is
30# some incentive to fix them eventually.
31CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
32		-Wno-error-parentheses-equality -Wno-unused-function \
33		${NO_WFORMAT}
34.endif
35
36# External compilers may not support our format extensions.  Allow them
37# to be disabled.  WARNING: format checking is disabled in this case.
38.if ${MK_FORMAT_EXTENSIONS} == "no"
39NO_WFORMAT=		-Wno-format
40.else
41FORMAT_EXTENSIONS=	-fformat-extensions
42.endif
43
44#
45# On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
46# and above adds code to the entry and exit point of every function to align the
47# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
48# per function call.  While the 16-byte alignment may benefit micro benchmarks,
49# it is probably an overall loss as it makes the code bigger (less efficient
50# use of code cache tag lines) and uses more stack (less efficient use of data
51# cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
52# operations inside the kernel itself.  These operations are exclusively
53# reserved for user applications.
54#
55# gcc:
56# Setting -mno-mmx implies -mno-3dnow
57# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
58#
59# clang:
60# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
61# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
62#
63.if ${MACHINE_CPUARCH} == "i386"
64.if ${COMPILER_TYPE} != "clang"
65CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
66.else
67CFLAGS+=	-mno-aes -mno-avx
68.endif
69CFLAGS+=	-mno-mmx -mno-sse -msoft-float
70INLINE_LIMIT?=	8000
71.endif
72
73.if ${MACHINE_CPUARCH} == "arm"
74INLINE_LIMIT?=	8000
75.endif
76
77#
78# For IA-64, we use r13 for the kernel globals pointer and we only use
79# a very small subset of float registers for integer divides.
80#
81.if ${MACHINE_CPUARCH} == "ia64"
82CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
83INLINE_LIMIT?=	15000
84.endif
85
86#
87# For sparc64 we want the medany code model so modules may be located
88# anywhere in the 64-bit address space.  We also tell GCC to use floating
89# point emulation.  This avoids using floating point registers for integer
90# operations which it has a tendency to do.
91#
92.if ${MACHINE_CPUARCH} == "sparc64"
93CFLAGS+=	-mcmodel=medany -msoft-float
94INLINE_LIMIT?=	15000
95.endif
96
97#
98# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
99# operations inside the kernel itself.  These operations are exclusively
100# reserved for user applications.
101#
102# gcc:
103# Setting -mno-mmx implies -mno-3dnow
104# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
105#
106# clang:
107# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
108# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
109# (-mfpmath= is not supported)
110#
111.if ${MACHINE_CPUARCH} == "amd64"
112.if ${COMPILER_TYPE} == "clang"
113CFLAGS+=	-mno-aes -mno-avx
114.endif
115CFLAGS+=	-mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
116		-fno-asynchronous-unwind-tables
117INLINE_LIMIT?=	8000
118.endif
119
120#
121# For PowerPC we tell gcc to use floating point emulation.  This avoids using
122# floating point registers for integer operations which it has a tendency to do.
123# Also explicitly disable Altivec instructions inside the kernel.
124#
125.if ${MACHINE_CPUARCH} == "powerpc"
126CFLAGS+=	-msoft-float -mno-altivec
127INLINE_LIMIT?=	15000
128.endif
129
130#
131# Use dot symbols on powerpc64 to make ddb happy
132#
133.if ${MACHINE_ARCH} == "powerpc64"
134CFLAGS+=	-mcall-aixdesc
135.endif
136
137#
138# For MIPS we also tell gcc to use floating point emulation
139#
140.if ${MACHINE_CPUARCH} == "mips"
141CFLAGS+=	-msoft-float
142INLINE_LIMIT?=	8000
143.endif
144
145#
146# GCC 3.0 and above like to do certain optimizations based on the
147# assumption that the program is linked against libc.  Stop this.
148#
149CFLAGS+=	-ffreestanding
150
151#
152# GCC SSP support
153#
154.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
155    ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
156CFLAGS+=	-fstack-protector
157.endif
158