arch/x86/Makefile.um

Source file repositories/reference/linux-study-clean/arch/x86/Makefile.um

File Facts

System
Linux kernel
Corpus path
arch/x86/Makefile.um
Extension
.um
Size
2037 bytes
Lines
74
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: build/configuration rule
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

# SPDX-License-Identifier: GPL-2.0
core-y += arch/x86/crypto/

#
# Disable SSE and other FP/SIMD instructions to match normal x86
# This is required to work around issues in older LLVM versions, but breaks
# GCC versions < 11. See:
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99652
#
ifeq ($(call gcc-min-version, 110000)$(CONFIG_CC_IS_CLANG),y)
KBUILD_CFLAGS +=  -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
endif

KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json

# The target.json file is not available when invoking rustc-option, so use the
# built-in target when checking whether flags are supported instead.
ifeq ($(CONFIG_X86_32),y)
KBUILD_RUSTFLAGS_OPTION_CHKS += --target=i686-unknown-linux-gnu
else
KBUILD_RUSTFLAGS_OPTION_CHKS += --target=x86_64-unknown-linux-gnu
endif

ifeq ($(CONFIG_X86_32),y)
START := 0x8048000

KBUILD_LDFLAGS		+= -m elf_i386
ELF_ARCH		:= i386
ELF_FORMAT 		:= elf32-i386
CHECKFLAGS	+= -D__i386__

KBUILD_CFLAGS		+= $(call cc-option,-m32)
KBUILD_AFLAGS		+= $(call cc-option,-m32)
LINK-y			+= $(call cc-option,-m32)

LDS_EXTRA		:= -Ui386
export LDS_EXTRA

# First of all, tune CFLAGS for the specific CPU. This actually sets cflags-y.
include $(srctree)/arch/x86/Makefile_32.cpu

# prevent gcc from keeping the stack 16 byte aligned. Taken from i386.
cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)

# Prevent sprintf in nfsd from being converted to strcpy and resulting in
# an unresolved reference.
cflags-y += -ffreestanding

KBUILD_CFLAGS += $(cflags-y)

else

START := 0x60000000

KBUILD_CFLAGS += -fno-builtin -m64 

CHECKFLAGS  += -m64 -D__x86_64__
KBUILD_AFLAGS += -m64
KBUILD_LDFLAGS += -m elf_x86_64
KBUILD_CPPFLAGS += -m64

ELF_ARCH := i386:x86-64
ELF_FORMAT := elf64-x86-64

# Not on all 64-bit distros /lib is a symlink to /lib64. PLD is an example.

LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib64
LINK-y += -m64

Annotation

Implementation Notes