| Message ID | 20230505071850.228734-2-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc/64: ELFv2 conversion | expand |
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 <nathan@kernel.org> > Signed-off-by: Nicholas Piggin <npiggin@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 <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@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 >
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 + 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))
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 <nathan@kernel.org> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/Kconfig | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)