Error building Android kernel: "multiple target patterns"

I attempted to build a fresh kernel for Nexus 5X following Google's instructions on this page

• Build system: Ubuntu 14.04 x86_64
• Target system: MTC19T/bullhead (Actually any marshmallow version on 5X)
• Toolchain: android-6.0.1_r25/prebuilts/gcc/linux-x86/aarch64/

Exact sequence of commands I executed are:

$ git clone https://android.googlesource.com/kernel/msm$ export ARCH=arm64$ export CROSS_COMPILE=aarch64-linux-android-$ cd msm$ git checkout -b android-msm-bullhead-3.10-marshmallow-mr1 origin/android-msm-bullhead-3.10-marshmallow-mr1$ make bullhead_defconfig$ make

I am greeted with following error after last command:

Makefile:796: *** multiple target patterns.  Stop.

Investigations:

Now line 796 in makefile is:

vmlinux: scripts/link-vmlinux.sh $(vmlinux-deps) FORCE

and other relevant lines are:

vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y) $(drivers-y) $(net-y)export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds

I found that if I remove $(libs-y) from $(KBUILD_VMLINUX_MAIN) this error disappears, and build continues for some time. I am sure I wil find some or other issue later, so I decided to debug further.

Disclaimer: Rest of this is a bit gray area for me

$(libs-y) is defined as:

libs-y      := lib/libs-y1     := $(patsubst %/, %/lib.a, $(libs-y))libs-y2     := $(patsubst %/, %/built-in.o, $(libs-y))libs-y      := $(libs-y1) $(libs-y2)

So I called scripts/link-vmlinux.sh with parameters lib/lib.a lib/built-in.o FORCE and am greeted with this error:

gps@gps-HP-ProBook-4540s:~/andsrc/kernel/msm$ ./scripts/link-vmlinux.sh lib/lib.a lib/built-in.o FORCEtrap: SIGHUP: bad trap

Since this output has :, this probably explains the original make error.

Now, disabling the line containing trap does not help, we get another error:

gps@gps-HP-ProBook-4540s:~/andsrc/kernel/msm$ ./scripts/link-vmlinux.sh lib/lib.a lib/built-in.o FORCE  LD      vmlinux.o./scripts/link-vmlinux.sh: 44: ./scripts/link-vmlinux.sh: -r: not found

I am not very sure what to try next. Any help is appreciated.