xref: /freebsd/sys/conf/kern.mk (revision 2357939bc239bd5334a169b62313806178dd8f30)
1# $FreeBSD$
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
11CWARNFLAGS=
12.else
13CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
14		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
15		-fformat-extensions -std=c99
16.endif
17#
18# The following flags are next up for working on:
19#	-W
20
21#
22# On the i386, do not align the stack to 16-byte boundaries.  Otherwise GCC
23# 2.95 adds code to the entry and exit point of every function to align the
24# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
25# per function call.  While the 16-byte alignment may benefit micro benchmarks,
26# it is probably an overall loss as it makes the code bigger (less efficient
27# use of code cache tag lines) and uses more stack (less efficient use of data
28# cache tag lines)
29#
30.if ${MACHINE_ARCH} == "i386" && ${CC} != "icc"
31CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
32INLINE_LIMIT?=	8000
33.endif
34
35#
36# On the alpha, make sure that we don't use floating-point registers and
37# allow the use of BWX etc instructions (only needed for low-level i/o).
38# Also, reserve register t7 to point at per-cpu global variables.
39#
40.if ${MACHINE_ARCH} == "alpha"
41CFLAGS+=	-mno-fp-regs -ffixed-8 -Wa,-mev6
42INLINE_LIMIT?=	15000
43.endif
44
45#
46# For IA-64, we use r13 for the kernel globals pointer and we only use
47# a very small subset of float registers for integer divides.
48#
49.if ${MACHINE_ARCH} == "ia64"
50CFLAGS+=	-ffixed-r13 -mfixed-range=f32-f127 -mno-sdata
51INLINE_LIMIT?=	15000
52.endif
53
54#
55# For sparc64 we want medlow code model, and we tell gcc to use floating
56# point emulation.  This avoids using floating point registers for integer
57# operations which it has a tendency to do.
58#
59.if ${MACHINE_ARCH} == "sparc64"
60CFLAGS+=	-mcmodel=medlow -msoft-float
61INLINE_LIMIT?=	15000
62.endif
63
64#
65# For AMD64, use a medium model for now.  We'll switch to "kernel"
66# once pmap is ready.  Be excessively careful to not generate FPU code.
67#
68.if ${MACHINE_ARCH} == "amd64"
69CFLAGS+=	-mcmodel=kernel -mno-red-zone \
70		-mfpmath=387 -mno-sse -mno-sse2 -mno-mmx -mno-3dnow \
71		-msoft-float -fno-asynchronous-unwind-tables
72INLINE_LIMIT?=	8000
73.endif
74
75#
76# For PowerPC we tell gcc to use floating point emulation.  This avoids using
77# floating point registers for integer operations which it has a tendency to do.
78#
79.if ${MACHINE_ARCH} == "powerpc"
80CFLAGS+=	-msoft-float
81INLINE_LIMIT?=	15000
82.endif
83
84#
85# GCC 3.0 and above like to do certain optimizations based on the
86# assumption that the program is linked against libc.  Stop this.
87#
88.if ${CC} == "icc"
89CFLAGS+=	-nolib_inline
90.else
91CFLAGS+=	-ffreestanding
92.endif
93
94.if ${CC} == "icc"
95CFLAGS+=	-restrict
96.endif
97