[llvm-bugs] [Bug 45632] New: Linux kernel's multi_v5_defconfig no longer boots after max-page-size increase to 64k

via llvm-bugs llvm-bugs at lists.llvm.org
Tue Apr 21 13:31:20 PDT 2020


https://bugs.llvm.org/show_bug.cgi?id=45632

            Bug ID: 45632
           Summary: Linux kernel's multi_v5_defconfig no longer boots
                    after max-page-size increase to 64k
           Product: lld
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: ELF
          Assignee: unassignedbugs at nondot.org
          Reporter: natechancellor at gmail.com
                CC: llvm-bugs at lists.llvm.org, smithp352 at googlemail.com

https://github.com/llvm/llvm-project/commit/87383e408d41623ada41e2bbc371b037fa29e894

To reproduce (assuming LLVM/clang, arm-linux-gnueabi binutils, zstd, and
qemu-system-arm are in your PATH):

$ git clone -b v5.7-rc2
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

$ git clone https://github.com/ClangBuiltLinux/boot-utils

$ make -C linux -j$(nproc) -s ARCH=arm CC=clang
CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 O=out/arm32 distclean
multi_v5_defconfig zImage aspeed-bmc-opp-palmetto.dtb

$ ./boot-utils/boot-qemu.sh -a arm32_v5 -k linux/out/arm32 -t 30s
...
+ RET=124
...

To test the behavior before that change:

$ sed -i '55 a KBUILD_LDFLAGS\t+= -z max-page-size=4096'
linux/arch/arm/Makefile

$ make -C linux -j$(nproc) -s ARCH=arm CC=clang
CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 O=out/arm32 distclean
multi_v5_defconfig zImage aspeed-bmc-opp-palmetto.dtb

$ ./boot-utils/boot-qemu.sh -a arm32_v5 -k linux/out/arm32 -t 30s
...
Linux version 5.7.0-rc2-dirty (nathan at ubuntu-s3-xlarge-x86) (ClangBuiltLinux
clang version 11.0.0 (git://github.com/llvm/llvm-project
a9b137f9ffba8cb25dfd7dd1fb613e8aac121b37), LLD 11.0.0
(git://github.com/llvm/llvm-project a9b137f9ffba8cb25dfd7dd1fb613e8aac121b37))
#1 PREEMPT Tue Apr 21 13:21:14
...

I am unsure of how to debug this further. I tried attaching gdb to vmlinux but
it looks like the boot gets stuck extremely early, it does not even make it to
start_kernel.

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