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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Fri, 13 Jan 2023 12:58:06 +0100
Message-ID: <CAMj1kXH3hoGWF=c7UVsWi3xoJsJ1VyFK74CV+L8SO8u2o2xdsQ@mail.gmail.com>
Subject: Re: linker problem with Ubuntu 18.04 tool chain: unknown architecture
 of input file `arch/arm64/boot/vmlinuz.o' is incompatible with aarch64 output
To:     Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc:     linux-efi@vger.kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Jeremy Linton <jeremy.linton@arm.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Precedence: bulk

On Fri, 13 Jan 2023 at 12:50, Lukas Bulwahn <lukas.bulwahn@gmail.com> wrote:
>
> Dear Ard,
>
> with my Ubuntu 18.04 arm gcc tool chain, I encounter this linker error
> in my allyesconfig build:
>
>  LD      arch/arm64/boot/vmlinuz.efi.elf
> aarch64-linux-gnu-ld: unknown architecture of input file
> `arch/arm64/boot/vmlinuz.o' is incompatible with aarch64 output
> drivers/firmware/efi/libstub/Makefile.zboot:41: recipe for target
> 'arch/arm64/boot/vmlinuz.efi.elf' failed
> make[1]: *** [arch/arm64/boot/vmlinuz.efi.elf] Error 1
> arch/arm64/Makefile:173: recipe for target 'vmlinuz.efi' failed
> make: *** [vmlinuz.efi] Error 2
>
> I bisected it back to happen since commit c37b830fef13 ("arm64: efi:
> enable generic EFI compressed boot"), and it still appears with the
> latest next-20230113 (on linux-next, I have to remove DRM_MSM as it
> currently comes with a build error).
>
> The specific compiler and linker versions on my system are:
>
> $ aarch64-linux-gnu-ld --version
> GNU ld (GNU Binutils for Ubuntu) 2.30
>
> $ aarch64-linux-gnu-gcc --version
> aarch64-linux-gnu-gcc (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04) 7.5.0
>
>
> IMHO, I run pretty standard commands:
> make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j 32 mrproper
> make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j 32 allyesconfig
> make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j 32 all
>
> Let me know if you need more information.
>

Hello Lukas,

This seems to mean that AArch64 ld.bfd 2.30 is not able to combine
generic ELF objects with AArch64 ELF objects. vmlinuz.o only contains
a compressed blob in an ELF data section, and more modern toolchains
have no issue with this at all.

Given that building allyesconfig with fairly outdated toolchains is
not something anyone is likely to obsess about, I don't have a strong
preference as to how we work around this, put perhaps the easiest
approach would be for CONFIG_EFI_ZBOOT to depend on !CONFIG_LD_IS_BFD
|| CONFIG_LD_VERSION >= 23xxx here? (We'll need to check the exact
version)