Re: [PATCH] KVM: arm64: Disable LTO in hyp
From: Marc Zyngier <maz@kernel.org>
Date: 2021-03-04 19:17:22
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kvmarm, lkml
On Thu, 04 Mar 2021 18:45:44 +0000, Sami Tolvanen [off-list ref] wrote:
allmodconfig + CONFIG_LTO_CLANG_THIN=y fails to build due to following linker errors: ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21CC):
I assume this message is only an oddity, right? Because __guest_enter() is as far as you can imagine from irqbypass.c...
relocation R_AARCH64_CONDBR19 out of range: 2031220 is not in [-1048576, 1048575]; references hyp_panic >>> defined in vmlinux.o ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21E0): relocation R_AARCH64_ADR_PREL_LO21 out of range: 2031200 is not in [-1048576, 1048575]; references hyp_panic >>> defined in vmlinux.o As LTO is not really necessary for the hypervisor code, disable it for the hyp directory to fix the build.
Can you shed some light on what the problem is exactly?
quoted hunk ↗ jump to hunk
Link: https://github.com/ClangBuiltLinux/linux/issues/1317 Reported-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/kvm/hyp/Makefile | 3 +++ 1 file changed, 3 insertions(+)diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index 687598e41b21..e8116016e6a8 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile@@ -11,3 +11,6 @@ subdir-ccflags-y := -I$(incdir) \ $(DISABLE_STACKLEAK_PLUGIN) obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o + +# Disable LTO for the files in this directory +KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))base-commit: f69d02e37a85645aa90d18cacfff36dba370f797
Can this be reduced to the nvhe part of the tree? The rest of the hypervisor should support being built with LTO, I'd expect. Or am I missing something more significant? Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel