xref: /freebsd-10.1-release/sys/conf/kern.mk

# $FreeBSD$

#
# Warning flags for compiling the kernel and components of the kernel:
#
CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
		-Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
		-Wmissing-include-dirs -fdiagnostics-show-option \
		${CWARNEXTRA}
#
# The following flags are next up for working on:
#	-Wextra

# Disable a few warnings for clang, since there are several places in the
# kernel where fixing them is more trouble than it is worth, or where there is
# a false positive.
.if ${COMPILER_TYPE} == "clang"
NO_WCONSTANT_CONVERSION=	-Wno-constant-conversion
NO_WARRAY_BOUNDS=		-Wno-array-bounds
NO_WSHIFT_COUNT_NEGATIVE=	-Wno-shift-count-negative
NO_WSHIFT_COUNT_OVERFLOW=	-Wno-shift-count-overflow
NO_WUNUSED_VALUE=		-Wno-unused-value
NO_WSELF_ASSIGN=		-Wno-self-assign
NO_WFORMAT_SECURITY=		-Wno-format-security
NO_WUNNEEDED_INTERNAL_DECL=	-Wno-unneeded-internal-declaration
NO_WSOMETIMES_UNINITIALIZED=	-Wno-error-sometimes-uninitialized
# Several other warnings which might be useful in some cases, but not severe
# enough to error out the whole kernel build.  Display them anyway, so there is
# some incentive to fix them eventually.
CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
		-Wno-error-parentheses-equality -Wno-error-unused-function \
		${NO_WFORMAT}
.endif

# External compilers may not support our format extensions.  Allow them
# to be disabled.  WARNING: format checking is disabled in this case.
.if ${MK_FORMAT_EXTENSIONS} == "no"
NO_WFORMAT=		-Wno-format
.else
FORMAT_EXTENSIONS=	-fformat-extensions
.endif

#
# On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
# and above adds code to the entry and exit point of every function to align the
# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
# per function call.  While the 16-byte alignment may benefit micro benchmarks,
# it is probably an overall loss as it makes the code bigger (less efficient
# use of code cache tag lines) and uses more stack (less efficient use of data
# cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
# operations inside the kernel itself.  These operations are exclusively
# reserved for user applications.
#
# gcc:
# Setting -mno-mmx implies -mno-3dnow
# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
#
# clang:
# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
#
.if ${MACHINE_CPUARCH} == "i386"
.if ${COMPILER_TYPE} != "clang"
CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
.else
CFLAGS+=	-mno-aes -mno-avx
.endif
CFLAGS+=	-mno-mmx -mno-sse -msoft-float
INLINE_LIMIT?=	8000
.endif

.if ${MACHINE_CPUARCH} == "arm"
INLINE_LIMIT?=	8000
.endif

#
# For IA-64, we use r13 for the kernel globals pointer and we only use
# a very small subset of float registers for integer divides.
#
.if ${MACHINE_CPUARCH} == "ia64"
CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
INLINE_LIMIT?=	15000
.endif

#
# For sparc64 we want the medany code model so modules may be located
# anywhere in the 64-bit address space.  We also tell GCC to use floating
# point emulation.  This avoids using floating point registers for integer
# operations which it has a tendency to do.
#
.if ${MACHINE_CPUARCH} == "sparc64"
.if ${COMPILER_TYPE} == "clang"
CFLAGS+=	-mcmodel=large -fno-dwarf2-cfi-asm
.else
CFLAGS+=	-mcmodel=medany -msoft-float
.endif
INLINE_LIMIT?=	15000
.endif

#
# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
# operations inside the kernel itself.  These operations are exclusively
# reserved for user applications.
#
# gcc:
# Setting -mno-mmx implies -mno-3dnow
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
#
# clang:
# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
# (-mfpmath= is not supported)
#
.if ${MACHINE_CPUARCH} == "amd64"
.if ${COMPILER_TYPE} == "clang"
CFLAGS+=	-mno-aes -mno-avx
.endif
CFLAGS+=	-mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
		-fno-asynchronous-unwind-tables
INLINE_LIMIT?=	8000
.endif

#
# For PowerPC we tell gcc to use floating point emulation.  This avoids using
# floating point registers for integer operations which it has a tendency to do.
# Also explicitly disable Altivec instructions inside the kernel.
#
.if ${MACHINE_CPUARCH} == "powerpc"
CFLAGS+=	-msoft-float -mno-altivec
INLINE_LIMIT?=	15000
.endif

#
# Use dot symbols on powerpc64 to make ddb happy
#
.if ${MACHINE_ARCH} == "powerpc64"
CFLAGS+=	-mcall-aixdesc
.endif

#
# For MIPS we also tell gcc to use floating point emulation
#
.if ${MACHINE_CPUARCH} == "mips"
CFLAGS+=	-msoft-float
INLINE_LIMIT?=	8000
.endif

#
# GCC 3.0 and above like to do certain optimizations based on the
# assumption that the program is linked against libc.  Stop this.
#
CFLAGS+=	-ffreestanding

#
# GCC SSP support
#
.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
    ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
CFLAGS+=	-fstack-protector
.endif

#
# Add -gdwarf-2 when compiling -g
#
.if ${COMPILER_TYPE} == "clang" && ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf} == ""
CFLAGS+=	-gdwarf-2
.endif