Re: [PATCH] efi/libstub: avoid linking libstub/lib-ksyms.o into vmlinux

[Ard Biesheuvel]

On Thu, 5 Mar 2020 at 06:50, Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> drivers/firmware/efi/libstub/Makefile is supposed to create a static
> library, which is not directly linked to vmlinux.
>

This is not true for arm64. Does that matter?

> Since commit 7f2084fa55e6 ("[kbuild] handle exports in lib-y objects
> reliably"), any Makefile using lib-y generates lib-ksyms.o which is
> linked into vmlinux.
>
> In this case, the following garbage object is linked into vmlinux.
>
>   drivers/firmware/efi/libstub/lib-ksyms.o
>
> We do not want to link anything from libstub/ directly to vmlinux,
> so using subdir-y instead of obj-y is the correct way to descend into
> this directory.
>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---
>
>  drivers/firmware/efi/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index 554d795270d9..4fd2fa02f549 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -19,7 +19,7 @@ obj-$(CONFIG_EFI_VARS_PSTORE)         += efi-pstore.o
>  obj-$(CONFIG_UEFI_CPER)                        += cper.o
>  obj-$(CONFIG_EFI_RUNTIME_MAP)          += runtime-map.o
>  obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)     += runtime-wrappers.o
> -obj-$(CONFIG_EFI_STUB)                 += libstub/
> +subdir-$(CONFIG_EFI_STUB)              += libstub
>  obj-$(CONFIG_EFI_FAKE_MEMMAP)          += fake_map.o
>  obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)   += efibc.o
>  obj-$(CONFIG_EFI_TEST)                 += test/
> --
> 2.17.1
>