3ad1a09169
add it in kern.mk, but only if we're using clang. While this option is supported by both clang and gcc, in the future there may be changes to clang which change the defaults that require a tweak to build our kernel such that other tools in our tree will work. Set a good example by forcing -gdwarf-2 only for clang builds, and only if the user hasn't specified another dwarf level already. Update UPDATING to reflect the changed state of affairs. This also keeps us from having to update all the ARM kernels to add this, and also keeps us from in the future having to update all the MIPS kernels and is one less place the user will have to know to do something special for clang and one less thing developers will need to do when moving an architecture to clang. Reviewed by: ian@ MFC after: 1 week
172 lines
5.3 KiB
Makefile
172 lines
5.3 KiB
Makefile
# $FreeBSD$
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# Compat
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MK_FORMAT_EXTENSIONS?=no
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#
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# Warning flags for compiling the kernel and components of the kernel:
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#
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CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
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-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
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-Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
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-Wmissing-include-dirs -fdiagnostics-show-option \
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${CWARNEXTRA}
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#
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# The following flags are next up for working on:
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# -Wextra
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# Disable a few warnings for clang, since there are several places in the
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# kernel where fixing them is more trouble than it is worth, or where there is
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# a false positive.
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.if ${COMPILER_TYPE} == "clang"
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NO_WCONSTANT_CONVERSION= -Wno-constant-conversion
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NO_WARRAY_BOUNDS= -Wno-array-bounds
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NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
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NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
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NO_WUNUSED_VALUE= -Wno-unused-value
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NO_WSELF_ASSIGN= -Wno-self-assign
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NO_WFORMAT_SECURITY= -Wno-format-security
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NO_WUNNEEDED_INTERNAL_DECL= -Wno-unneeded-internal-declaration
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NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
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# Several other warnings which might be useful in some cases, but not severe
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# enough to error out the whole kernel build. Display them anyway, so there is
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# some incentive to fix them eventually.
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CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
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-Wno-error-parentheses-equality -Wno-unused-function \
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${NO_WFORMAT}
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.endif
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# External compilers may not support our format extensions. Allow them
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# to be disabled. WARNING: format checking is disabled in this case.
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.if ${MK_FORMAT_EXTENSIONS} == "no"
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NO_WFORMAT= -Wno-format
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.else
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FORMAT_EXTENSIONS= -fformat-extensions
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.endif
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#
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# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
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# and above adds code to the entry and exit point of every function to align the
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# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
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# per function call. While the 16-byte alignment may benefit micro benchmarks,
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# it is probably an overall loss as it makes the code bigger (less efficient
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# use of code cache tag lines) and uses more stack (less efficient use of data
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# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
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# operations inside the kernel itself. These operations are exclusively
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# reserved for user applications.
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#
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# gcc:
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# Setting -mno-mmx implies -mno-3dnow
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# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
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#
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# clang:
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# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
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# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
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#
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.if ${MACHINE_CPUARCH} == "i386"
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.if ${COMPILER_TYPE} != "clang"
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CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2
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.else
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CFLAGS+= -mno-aes -mno-avx
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.endif
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CFLAGS+= -mno-mmx -mno-sse -msoft-float
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INLINE_LIMIT?= 8000
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.endif
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.if ${MACHINE_CPUARCH} == "arm"
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INLINE_LIMIT?= 8000
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.endif
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#
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# For IA-64, we use r13 for the kernel globals pointer and we only use
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# a very small subset of float registers for integer divides.
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#
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.if ${MACHINE_CPUARCH} == "ia64"
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CFLAGS+= -ffixed-r13 -mfixed-range=f32-f127 -fpic #-mno-sdata
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INLINE_LIMIT?= 15000
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.endif
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#
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# For sparc64 we want the medany code model so modules may be located
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# anywhere in the 64-bit address space. We also tell GCC to use floating
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# point emulation. This avoids using floating point registers for integer
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# operations which it has a tendency to do.
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#
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.if ${MACHINE_CPUARCH} == "sparc64"
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.if ${COMPILER_TYPE} == "clang"
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CFLAGS+= -mcmodel=large -fno-dwarf2-cfi-asm
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.else
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CFLAGS+= -mcmodel=medany -msoft-float
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.endif
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INLINE_LIMIT?= 15000
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.endif
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#
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# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
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# operations inside the kernel itself. These operations are exclusively
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# reserved for user applications.
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#
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# gcc:
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# Setting -mno-mmx implies -mno-3dnow
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# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
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#
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# clang:
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# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
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# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
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# (-mfpmath= is not supported)
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#
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.if ${MACHINE_CPUARCH} == "amd64"
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.if ${COMPILER_TYPE} == "clang"
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CFLAGS+= -mno-aes -mno-avx
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.endif
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CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
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-fno-asynchronous-unwind-tables
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INLINE_LIMIT?= 8000
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.endif
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#
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# For PowerPC we tell gcc to use floating point emulation. This avoids using
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# floating point registers for integer operations which it has a tendency to do.
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# Also explicitly disable Altivec instructions inside the kernel.
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#
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.if ${MACHINE_CPUARCH} == "powerpc"
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CFLAGS+= -msoft-float -mno-altivec
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INLINE_LIMIT?= 15000
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.endif
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#
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# Use dot symbols on powerpc64 to make ddb happy
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#
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.if ${MACHINE_ARCH} == "powerpc64"
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CFLAGS+= -mcall-aixdesc
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.endif
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#
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# For MIPS we also tell gcc to use floating point emulation
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#
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.if ${MACHINE_CPUARCH} == "mips"
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CFLAGS+= -msoft-float
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INLINE_LIMIT?= 8000
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.endif
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#
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# GCC 3.0 and above like to do certain optimizations based on the
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# assumption that the program is linked against libc. Stop this.
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#
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CFLAGS+= -ffreestanding
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#
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# GCC SSP support
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#
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.if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
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${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
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CFLAGS+= -fstack-protector
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.endif
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#
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# Add -gdwarf-2 when compiling -g
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#
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.if ${COMPILER_TYPE} == "clang" && ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf} == ""
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CFLAGS+= -gdwarf-2
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.endif
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