u-boot-brain/arch/sandbox/config.mk
Marek Behún 958f2e57ef build: use thin archives instead of incremental linking
Currently we use incremental linking (ld -r) to link several object
files from one directory into one built-in.o object file containing the
linked code from that directory (and its subdirectories).

Linux has, some time ago, moved to thin archives instead.

Thin archives are archives (.a) that do not really contain the object
files, only references to them.

Using thin archives instead of incremental linking
- saves disk space
- apparently works better with dead code elimination
- makes things easier for LTO

The third point is the important one for us. With incremental linking
there are several options how to do LTO, and that would unnecessarily
complicate things.

We have to use the --whole-archive/--no-whole-archive linking option
instead of --start-group/--end-group, otherwise linking may fail because
of unresolved symbols, or the resulting binary will be unusable.

We also need to use the P flag for ar, otherwise final linking may fail.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
2021-05-24 14:21:30 -04:00

62 lines
2.4 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2011 The Chromium OS Authors.
PLATFORM_CPPFLAGS += -D__SANDBOX__ -U_FORTIFY_SOURCE
PLATFORM_CPPFLAGS += -DCONFIG_ARCH_MAP_SYSMEM
PLATFORM_CPPFLAGS += -fPIC
PLATFORM_LIBS += -lrt
SDL_CONFIG ?= sdl2-config
# Define this to avoid linking with SDL, which requires SDL libraries
# This can solve 'sdl-config: Command not found' errors
ifneq ($(NO_SDL),)
PLATFORM_CPPFLAGS += -DSANDBOX_NO_SDL
else
PLATFORM_LIBS += $(shell $(SDL_CONFIG) --libs)
PLATFORM_CPPFLAGS += $(shell $(SDL_CONFIG) --cflags)
endif
cmd_u-boot__ = $(CC) -o $@ -Wl,-T u-boot.lds $(u-boot-init) \
-Wl,--whole-archive \
$(u-boot-main) \
-Wl,--no-whole-archive \
$(PLATFORM_LIBS) -Wl,-Map -Wl,u-boot.map
cmd_u-boot-spl = (cd $(obj) && $(CC) -o $(SPL_BIN) -Wl,-T u-boot-spl.lds \
$(patsubst $(obj)/%,%,$(u-boot-spl-init)) \
-Wl,--whole-archive \
$(patsubst $(obj)/%,%,$(u-boot-spl-main)) \
$(patsubst $(obj)/%,%,$(u-boot-spl-platdata)) \
-Wl,--no-whole-archive \
$(PLATFORM_LIBS) -Wl,-Map -Wl,u-boot-spl.map -Wl,--gc-sections)
CONFIG_ARCH_DEVICE_TREE := sandbox
ifeq ($(HOST_ARCH),$(HOST_ARCH_X86_64))
EFI_LDS := ${SRCDIR}/../../../arch/x86/lib/elf_x86_64_efi.lds
EFI_TARGET := --target=efi-app-x86_64
else ifeq ($(HOST_ARCH),$(HOST_ARCH_X86))
EFI_LDS := ${SRCDIR}/../../../arch/x86/lib/elf_ia32_efi.lds
EFI_TARGET := --target=efi-app-ia32
else ifeq ($(HOST_ARCH),$(HOST_ARCH_AARCH64))
EFI_LDS := ${SRCDIR}/../../../arch/arm/lib/elf_aarch64_efi.lds
OBJCOPYFLAGS += -j .text -j .secure_text -j .secure_data -j .rodata -j .data \
-j .u_boot_list -j .rela.dyn -j .got -j .got.plt \
-j .binman_sym_table -j .text_rest \
-j .efi_runtime -j .efi_runtime_rel
else ifeq ($(HOST_ARCH),$(HOST_ARCH_ARM))
EFI_LDS := ${SRCDIR}/../../../arch/arm/lib/elf_arm_efi.lds
OBJCOPYFLAGS += -j .text -j .secure_text -j .secure_data -j .rodata -j .hash \
-j .data -j .got -j .got.plt -j .u_boot_list -j .rel.dyn \
-j .binman_sym_table -j .text_rest \
-j .efi_runtime -j .efi_runtime_rel
else ifeq ($(HOST_ARCH),$(HOST_ARCH_RISCV32))
EFI_LDS := ${SRCDIR}/../../../arch/riscv/lib/elf_riscv32_efi.lds
else ifeq ($(HOST_ARCH),$(HOST_ARCH_RISCV64))
EFI_LDS := ${SRCDIR}/../../../arch/riscv/lib/elf_riscv64_efi.lds
endif
EFI_CRT0 := crt0_sandbox_efi.o
EFI_RELOC := reloc_sandbox_efi.o
AFLAGS_crt0_sandbox_efi.o += -DHOST_ARCH="$(HOST_ARCH)"
CFLAGS_reloc_sandbox_efi.o += -DHOST_ARCH="$(HOST_ARCH)"