path: root/arch/arc
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authorMasahiro Yamada <>2020-11-22 04:36:55 +0900
committerVineet Gupta <>2020-12-01 17:24:05 -0800
commitc5e6ae563c802c4d828d42e134af64004db2e58c (patch)
treede78a2bea7506d8d91cb37b8967c60afd2a8bcfc /arch/arc
parent0cfccb3c04934cdef42ae26042139f16e805b5f7 (diff)
ARC: build: move symlink creation to arch/arc/Makefile to avoid race
If you run 'make uImage uImage.gz' with the parallel option, uImage.gz will be created by two threads simultaneously. This is because arch/arc/Makefile does not specify the dependency between uImage and uImage.gz. Hence, GNU Make assumes they can be built in parallel. One thread descends into arch/arc/boot/ to create uImage, and another to create uImage.gz. Please notice the same log is displayed twice in the following steps: $ export CROSS_COMPILE=<your-arc-compiler-prefix> $ make -s ARCH=arc defconfig $ make -j$(nproc) ARCH=arc uImage uImage.gz [ snip ] LD vmlinux SORTTAB vmlinux SYSMAP OBJCOPY arch/arc/boot/vmlinux.bin OBJCOPY arch/arc/boot/vmlinux.bin GZIP arch/arc/boot/vmlinux.bin.gz GZIP arch/arc/boot/vmlinux.bin.gz UIMAGE arch/arc/boot/uImage.gz UIMAGE arch/arc/boot/uImage.gz Image Name: Linux-5.10.0-rc4-00003-g62f23044 Created: Sun Nov 22 02:52:26 2020 Image Type: ARC Linux Kernel Image (gzip compressed) Data Size: 2109376 Bytes = 2059.94 KiB = 2.01 MiB Load Address: 80000000 Entry Point: 80004000 Image arch/arc/boot/uImage is ready Image Name: Linux-5.10.0-rc4-00003-g62f23044 Created: Sun Nov 22 02:52:26 2020 Image Type: ARC Linux Kernel Image (gzip compressed) Data Size: 2815455 Bytes = 2749.47 KiB = 2.69 MiB Load Address: 80000000 Entry Point: 80004000 This is a race between the two threads trying to write to the same file arch/arc/boot/uImage.gz. This is a potential problem that can generate a broken file. I fixed a similar problem for ARM by commit 3939f3345050 ("ARM: 8418/1: add boot image dependencies to not generate invalid images"). I highly recommend to avoid such build rules that cause a race condition. Move the uImage rule to arch/arc/Makefile. Another strangeness is that arch/arc/boot/Makefile compares the timestamps between $(obj)/uImage and $(obj)/uImage.*: $(obj)/uImage: $(obj)/uImage.$(suffix-y) @ln -sf $(notdir $<) $@ @echo ' Image $@ is ready' This does not work as expected since $(obj)/uImage is a symlink. The symlink should be created in a phony target rule. I used $(kecho) instead of echo to suppress the message 'Image arch/arc/boot/uImage is ready' when the -s option is given. Signed-off-by: Masahiro Yamada <> Signed-off-by: Vineet Gupta <>
Diffstat (limited to 'arch/arc')
2 files changed, 13 insertions, 11 deletions
diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index cf9da9aea12a..578bdbbb0fa7 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -102,11 +102,22 @@ libs-y += arch/arc/lib/ $(LIBGCC)
boot := arch/arc/boot
-boot_targets := uImage uImage.bin uImage.gz uImage.lzma
+boot_targets := uImage.bin uImage.gz uImage.lzma
PHONY += $(boot_targets)
$(boot_targets): vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+uimage-default-y := uImage.bin
+uimage-default-$(CONFIG_KERNEL_GZIP) := uImage.gz
+uimage-default-$(CONFIG_KERNEL_LZMA) := uImage.lzma
+PHONY += uImage
+uImage: $(uimage-default-y)
+ @ln -sf $< $(boot)/uImage
+ @$(kecho) ' Image $(boot)/uImage is ready'
+CLEAN_FILES += $(boot)/uImage
$(Q)$(MAKE) $(clean)=$(boot)
diff --git a/arch/arc/boot/Makefile b/arch/arc/boot/Makefile
index 538b92f4dd25..3b1f8a69a89e 100644
--- a/arch/arc/boot/Makefile
+++ b/arch/arc/boot/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
-targets := vmlinux.bin vmlinux.bin.gz uImage
+targets := vmlinux.bin vmlinux.bin.gz
# uImage build relies on mkimage being availble on your host for ARC target
# You will need to build u-boot for ARC, rename mkimage to arc-elf32-mkimage
@@ -13,11 +13,6 @@ LINUX_START_TEXT = $$(readelf -h vmlinux | \
-suffix-y := bin
-suffix-$(CONFIG_KERNEL_GZIP) := gz
-suffix-$(CONFIG_KERNEL_LZMA) := lzma
-targets += uImage
targets += uImage.bin
targets += uImage.gz
targets += uImage.lzma
@@ -42,7 +37,3 @@ $(obj)/uImage.gz: $(obj)/vmlinux.bin.gz FORCE
$(obj)/uImage.lzma: $(obj)/vmlinux.bin.lzma FORCE
$(call if_changed,uimage,lzma)
-$(obj)/uImage: $(obj)/uImage.$(suffix-y)
- @ln -sf $(notdir $<) $@
- @echo ' Image $@ is ready'