[PATCH v5sub1 0/8] arm64: split linear and kernel mappings

On Mon, Feb 15, 2016 at 02:29:51PM +0100, Matthias Brugger wrote:

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On 12 February 2016 at 21:10, Matthias Brugger [off-list ref] wrote:

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On 12/02/16 20:47, Ard Biesheuvel wrote:

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On 12 February 2016 at 20:45, Matthias Brugger [off-list ref]

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I bisected linux-next (20160212) with the following error on booting with
an
initramfs:
  Failed to execute /init (error -8)
  request_module: runaway loop modprobe binfmt-464c
  Starting init: /sbin/init exists but couldn't execute it (error -8)
  request_module: runaway loop modprobe binfmt-464c
  Starting init: /bin/sh exists but couldn't execute it (error -8)
  Kernel panic - not syncing: No working init found.  Try passing init=
option to kernel. See Linux Documentation/init..

I tracked down the error to patch 7 of this series. But I realized that
patch 7 does not compile, but from patch 8 onwards I observe the error.

As far as this failure is concerned, I managed to reproduce an error
with patch #7 and not #8 applied, involving out of range kvm symbols
at link time. This is reproducible with GCC 4.8 but not GCC 4.9 or
later. Is this what you were seeing as well? Or is there another
problem?

I realized that I used " aarch64-linux-gnu-gcc (Linaro GCC 2014.11) 4.9.3
20141031 (prerelease)"  which gave me errors like:

arch/arm64/kvm/built-in.o: In function `__cpu_init_hyp_mode':
/home/mbrugger/src/linux-next/./arch/arm64/include/asm/kvm_host.h:331:(.text+0x73b4):
relocation truncated to fit: R_AARCH64_ADR_PREL_PG_HI21 against symbol
`__kvm_hyp_vector' defined in .hyp.text section in arch/arm64/kvm/built-in.o

So it was time to update my toolchain to "aarch64-linux-gnu-gcc (Linaro GCC
5.1-2015.08) 5.1.1 20150608" which fixed the problem for me.

FWIW, I've also been seeing a bunch of reloc errors with allmodconfig,
for-next/core and GCC 4.9. loops_per_jiffy was one of the problematic
symbols, iirc, but upgrading to GCC 6 (devel) fixed the issue.

Will