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 ${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-error-unused-function \
33		${NO_WFORMAT}
34.endif
35
36.if ${COMPILER_TYPE} == "gcc"
37# For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
38CWARNEXTRA?=	-Wno-uninitialized
39.endif
40
41# External compilers may not support our format extensions.  Allow them
42# to be disabled.  WARNING: format checking is disabled in this case.
43.if ${MK_FORMAT_EXTENSIONS} == "no"
44NO_WFORMAT=		-Wno-format
45.else
46FORMAT_EXTENSIONS=	-fformat-extensions
47.endif
48
49#
50# On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
51# and above adds code to the entry and exit point of every function to align the
52# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
53# per function call.  While the 16-byte alignment may benefit micro benchmarks,
54# it is probably an overall loss as it makes the code bigger (less efficient
55# use of code cache tag lines) and uses more stack (less efficient use of data
56# cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
57# operations inside the kernel itself.  These operations are exclusively
58# reserved for user applications.
59#
60# gcc:
61# Setting -mno-mmx implies -mno-3dnow
62# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
63#
64# clang:
65# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
66# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
67#
68.if ${MACHINE_CPUARCH} == "i386"
69.if ${COMPILER_TYPE} != "clang"
70CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
71.else
72CFLAGS+=	-mno-aes -mno-avx
73.endif
74CFLAGS+=	-mno-mmx -mno-sse -msoft-float
75INLINE_LIMIT?=	8000
76.endif
77
78.if ${MACHINE_CPUARCH} == "arm"
79INLINE_LIMIT?=	8000
80.endif
81
82#
83# For IA-64, we use r13 for the kernel globals pointer and we only use
84# a very small subset of float registers for integer divides.
85#
86.if ${MACHINE_CPUARCH} == "ia64"
87CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
88INLINE_LIMIT?=	15000
89.endif
90
91#
92# For sparc64 we want the medany code model so modules may be located
93# anywhere in the 64-bit address space.  We also tell GCC to use floating
94# point emulation.  This avoids using floating point registers for integer
95# operations which it has a tendency to do.
96#
97.if ${MACHINE_CPUARCH} == "sparc64"
98.if ${COMPILER_TYPE} == "clang"
99CFLAGS+=	-mcmodel=large -fno-dwarf2-cfi-asm
100.else
101CFLAGS+=	-mcmodel=medany -msoft-float
102.endif
103INLINE_LIMIT?=	15000
104.endif
105
106#
107# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
108# operations inside the kernel itself.  These operations are exclusively
109# reserved for user applications.
110#
111# gcc:
112# Setting -mno-mmx implies -mno-3dnow
113# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
114#
115# clang:
116# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
117# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
118# (-mfpmath= is not supported)
119#
120.if ${MACHINE_CPUARCH} == "amd64"
121.if ${COMPILER_TYPE} == "clang"
122CFLAGS+=	-mno-aes -mno-avx
123.endif
124CFLAGS+=	-mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
125		-fno-asynchronous-unwind-tables
126INLINE_LIMIT?=	8000
127.endif
128
129#
130# For PowerPC we tell gcc to use floating point emulation.  This avoids using
131# floating point registers for integer operations which it has a tendency to do.
132# Also explicitly disable Altivec instructions inside the kernel.
133#
134.if ${MACHINE_CPUARCH} == "powerpc"
135CFLAGS+=	-msoft-float -mno-altivec
136INLINE_LIMIT?=	15000
137.endif
138
139#
140# Use dot symbols on powerpc64 to make ddb happy
141#
142.if ${MACHINE_ARCH} == "powerpc64"
143CFLAGS+=	-mcall-aixdesc
144.endif
145
146#
147# For MIPS we also tell gcc to use floating point emulation
148#
149.if ${MACHINE_CPUARCH} == "mips"
150CFLAGS+=	-msoft-float
151INLINE_LIMIT?=	8000
152.endif
153
154#
155# GCC 3.0 and above like to do certain optimizations based on the
156# assumption that the program is linked against libc.  Stop this.
157#
158CFLAGS+=	-ffreestanding
159
160#
161# GCC SSP support
162#
163.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
164    ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
165CFLAGS+=	-fstack-protector
166.endif
167
168#
169# Add -gdwarf-2 when compiling -g
170#
171.if ${COMPILER_TYPE} == "clang" && ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf} == ""
172CFLAGS+=	-gdwarf-2
173.endif
174