Re: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G"

[Benjamin Gilbert]

On Wed, Jul 04, 2018 at 06:08:57PM +0300, Kirill A. Shutemov wrote:
> 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@xxxxxxxxxx>:
> > > > > 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():
> 
> 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.

Sure enough, we're passing LDFLAGS="" to make.  Your patch fixes the boot
failure for me.

--Benjamin Gilbert