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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Wed, 15 Jul 2020 09:51:12 +0300
Message-ID: <CAMj1kXHzZAqHbqgJnrTjxtRvcVkpZan3LC6khFEucdR=cUhYfg@mail.gmail.com>
Subject: Re: [PATCH] arch/x86/boot: Don't add the EFI stub to targets
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     X86 ML <x86@kernel.org>, Masahiro Yamada <masahiroy@kernel.org>,
        linux-kbuild@vger.kernel.org,
        linux-efi <linux-efi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, 15 Jul 2020 at 06:26, Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> vmlinux-objs-y is added to targets, which currently means that the EFI
> stub gets added to the targets as well. It shouldn't be added since it
> is built elsewhere.
>
> This confuses Makefile.build which interprets the EFI stub as a target
>         $(obj)/$(objtree)/drivers/firmware/efi/libstub/lib.a
> and will create drivers/firmware/efi/libstub/ underneath
> arch/x86/boot/compressed, to hold this supposed target, if building
> out-of-tree. [0]
>
> Fix this by pulling the stub out of vmlinux-objs-y into efi-obj-y.
>
> [0] See scripts/Makefile.build near the end:
>     # Create directories for object files if they do not exist
>
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  arch/x86/boot/compressed/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 7619742f91c9..5a828fde7a42 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -90,8 +90,8 @@ endif
>
>  vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
>
> -vmlinux-objs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
>  vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
> +efi-obj-$(CONFIG_EFI_STUB) = $(objtree)/drivers/firmware/efi/libstub/lib.a
>
>  # The compressed kernel is built with -fPIC/-fPIE so that a boot loader
>  # can place it anywhere in memory and it will still run. However, since
> @@ -115,7 +115,7 @@ endef
>  quiet_cmd_check-and-link-vmlinux = LD      $@
>        cmd_check-and-link-vmlinux = $(cmd_check_data_rel); $(cmd_ld)
>
> -$(obj)/vmlinux: $(vmlinux-objs-y) FORCE
> +$(obj)/vmlinux: $(vmlinux-objs-y) $(efi-obj-y) FORCE
>         $(call if_changed,check-and-link-vmlinux)
>
>  OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
> --
> 2.26.2
>