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SubjectRe: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G"
On Tue, Jul 03, 2018 at 05:21:50PM +0300, Kirill A. Shutemov wrote:
> On Tue, Jul 03, 2018 at 03:44:03PM +0300, Kirill A. Shutemov wrote:
> > On Tue, Jul 03, 2018 at 01:24:49PM +0200, Gabriel C wrote:
> > > 2018-07-01 23:32 GMT+02:00 Benjamin Gilbert <bgilbert@redhat.com>:
> > > > On Sun, Jul 01, 2018 at 05:15:59PM -0400, Benjamin Gilbert wrote:
> > > >> 4.17 kernels built with the CoreOS Container Linux toolchain and kconfig,
> > > >> up to and including 4.17.3, fail to boot on AMD64 running in (at least)
> > > >> QEMU/KVM. No messages are shown post-GRUB; the VM instantly reboots.
> > > >> Reverting commit 194a9749c73d ("x86/boot/compressed/64: Handle 5-level
> > > >> paging boot if kernel is above 4G") fixes it. I've attached our kernel
> > > >> config for reference, and am happy to test patches, provide sample QCOW
> > > >> images, etc.
> > > >
> > >
> > > Also see https://bugzilla.kernel.org/show_bug.cgi?id=200385 ,
> > >
> > > 0a1756bd2897951c03c1cb671bdfd40729ac2177 is acting up
> > > too with the same symptoms
> >
> > I tracked it down to -flto in LDFLAGS. I'll look more into this.
>
> -flto in LDFLAGS screws up this part of paging_prepare():

+Masahiro, Michal.

I've got it wrong. *Any* LDFLAGS option passed to make this way:

make LDFLAGS="..."

would cause a issue. Even empty.

It overrides all assignments to the variable in the makefile.
As result the image is built without -pie and linker doesn't generate
position independed code.

Looks like the patch below helps, but my make-fu is poor.
I don't see many override directives in kernel makefiles.
It makes me think that there's a better way to fix this.

Hm?

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index fa42f895fdde..4f24baa8cdeb 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -42,16 +42,16 @@ KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n
UBSAN_SANITIZE :=n

-LDFLAGS := -m elf_$(UTS_MACHINE)
+override LDFLAGS := -m elf_$(UTS_MACHINE)
# Compressed kernel should be built as PIE since it may be loaded at any
# address by the bootloader.
ifeq ($(CONFIG_X86_32),y)
-LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
+override LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
else
# To build 64-bit compressed kernel as PIE, we disable relocation
# overflow check to avoid relocation overflow error with a new linker
# command-line option, -z noreloc-overflow.
-LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
+override LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
&& echo "-z noreloc-overflow -pie --no-dynamic-linker")
endif
LDFLAGS_vmlinux := -T
--
Kirill A. Shutemov
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