From 032ce1ea9442e140a80e41078b5431d4c0fa2893 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 24 Apr 2025 12:19:18 +0200 Subject: [PATCH] x86/boot: Work around broken busybox 'truncate' tool The GNU coreutils version of truncate, which is the original, accepts a % prefix for the -s size argument which means the file in question should be padded to a multiple of the given size. This is currently used to pad the setup block of bzImage to a multiple of 4k before appending the decompressor. busybox reimplements truncate but does not support this idiom, and therefore fails the build since commit 9c54baab4401 ("x86/boot: Drop CRC-32 checksum and the build tool that generates it") Since very little build code within the kernel depends on the 'truncate' utility, work around this incompatibility by avoiding truncate altogether, and relying on dd to perform the padding. Fixes: 9c54baab4401 ("x86/boot: Drop CRC-32 checksum and the build tool that generates it") Reported-by: Tested-by: Philipp Stanner Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250424101917.1552527-2-ardb+git@google.com --- arch/x86/boot/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 81f55da81967..640fcac3af74 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -59,7 +59,7 @@ KBUILD_CFLAGS += $(CONFIG_CC_IMPLICIT_FALLTHROUGH) $(obj)/bzImage: asflags-y := $(SVGA_MODE) quiet_cmd_image = BUILD $@ - cmd_image = cp $< $@; truncate -s %4K $@; cat $(obj)/vmlinux.bin >>$@ + cmd_image = (dd if=$< bs=4k conv=sync status=none; cat $(filter-out $<,$(real-prereqs))) >$@ $(obj)/bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin FORCE $(call if_changed,image) -- 2.50.1