Hi Nick,
+ our mailing list, helps with review and making sure that we are not
missing anything :)
On Fri, May 05, 2023 at 05:18:47PM +1000, Nicholas Piggin wrote:
> The LLVM linker does not support ELFv1 at all, so BE kernels must be
> built with ELFv2. The LLD version check was added to be conservative,
> but previous LLD versions would simply fail to link ELFv1 entirely. The
> only would be to require LLD >= 15 for BE builds, but let's instead
> remove that restriction until proven otherwise (LLD 14.0 links a booting
> ELFv2 BE vmlinux for me).
>
> The minimum binutils has increased such that ELFv2 is always supported,
> so remove that check while we're here.
>
> Cc: Nathan Chancellor <nat...@kernel.org>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
Thanks for this change! I ran it through my (admittedly limited set of)
build tests with LD=ld.lld for big endian configurations and I saw no
build errors with LLVM 11.1.0 through 16.0.3 (and currently, a 17.0.0
built from main); my simple QEMU boot testing passed as well.
Reviewed-by: Nathan Chancellor <nat...@kernel.org>
Tested-by: Nathan Chancellor <nat...@kernel.org>
One small comment below.
> ---
> arch/powerpc/Kconfig | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index acffffbd5d77..e5d81645c902 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -624,10 +624,11 @@ config ARCH_HAS_KEXEC_PURGATORY
> def_bool KEXEC_FILE
>
> config PPC64_BIG_ENDIAN_ELF_ABI_V2
> - bool "Build big-endian kernel using ELF ABI V2 (EXPERIMENTAL)"
> + prompt "Build big-endian kernel using ELF ABI V2 (EXPERIMENTAL)" if
> LD_IS_BFD
> + bool
This could be
bool "Build big-endian kernel using ELF ABI V2 (EXPERIMENTAL)" if LD_IS_BFD
which is the syntactic sugar equivalent of what you already have.
The rest looks good to me.
> + default y if LD_IS_LLD
> depends on PPC64 && CPU_BIG_ENDIAN
> depends on CC_HAS_ELFV2
> - depends on LD_VERSION >= 22400 || LLD_VERSION >= 150000
> help
> This builds the kernel image using the "Power Architecture 64-Bit ELF
> V2 ABI Specification", which has a reduced stack overhead and faster
> @@ -638,8 +639,6 @@ config PPC64_BIG_ENDIAN_ELF_ABI_V2
> it is less well tested by kernel and toolchain. However some distros
> build userspace this way, and it can produce a functioning kernel.
>
> - This requires GCC and binutils 2.24 or newer.
> -
> config RELOCATABLE
> bool "Build a relocatable kernel"
> depends on PPC64 || (FLATMEM && (44x || PPC_85xx))
> --
> 2.40.1
>
