A similar issue exists for beaglev_defconfig:

[build 2023-09-23 10:34:44] mkdir -p `dirname /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/build/lib/sbi/sbi_tlb.o`; echo " CC        lib/sbi/sbi_tlb.o"; /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/host/bin/riscv64-buildroot-linux-gnu-gcc -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -O2 -fno-omit-frame-pointer -fno-optimize-sibling-calls -mno-save-restore -mstrict-align -mabi=lp64 -march=rv64imafdc -mcmodel=medany -I/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/platform/generic/include -I/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/include -I/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/lib/utils/libfdt/  -DFW_PIC -DFW_TEXT_START=0x80000000 -DFW_FDT_PATH=\"/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/images/u-boot.dtb\" -DFW_JUMP_ADDR=0x80200000 -DFW_JUMP_FDT_ADDR=0x82200000 -DFW_PAYLOAD_PATH=\"/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/images/u-boot.bin\" -DFW_PAYLOAD_OFFSET=0x200000 -DFW_PAYLOAD_FDT_ADDR=0x82200000  -fno-pie -no-pie -fPIE -pie -I/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/lib/sbi -D__OBJNAME__=sbi_tlb -c /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/lib/sbi/sbi_tlb.c -o /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/build/lib/sbi/sbi_tlb.o
[build 2023-09-23 10:34:44]  CC        lib/sbi/sbi_tlb.o
[build 2023-09-23 10:34:45] /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/lib/sbi/sbi_tlb.c: Assembler messages:
[build 2023-09-23 10:34:45] /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/lib/sbi/sbi_tlb.c:175: Error: unrecognized opcode `fence.i', extension `zifencei' required
[build 2023-09-23 10:34:45] make[1]: *** [Makefile:339: /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/build/lib/sbi/sbi_tlb.o] Error 1
[build 2023-09-23 10:34:45] make[1]: Leaving directory '/var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom'
[build 2023-09-23 10:34:45] make: *** [package/pkg-generic.mk:293: /var/lib/laminar/run/buildroot-beaglev_defconfig/6/buildroot/output/build/opensbi-custom/.stamp_built] Error 2

Jan-Benedict, All,

That second build log is eactly the original one; check the timestamps... :-/

The BeagleV defconfig uses an old opensbi: check if you can update it,
of maybe try to backport upstream 5d53b55aa77ffeefd4012445dfa6ad3535e1ff2c.

Also, it looks like all your reports are from an automated build farm, that
just builds all the defconfigs. We already do that once a week on our
gitlab.com repository. So, your reports are most probably duplicates of
the results we get once a week, e.g.:

    https://lore.kernel.org/buildroot/20230909062958.AE75B40A50@smtp2.osuosl.org/

If you look toward the end, you'll see the list of defconfigs that indeed
do not build.

Regards,
Yann E. MORIN.

Thank you for your report.

The issue tracker for the Buildroot project has been moved to
the Gitlab.com issue tracker:
    https://gitlab.com/buildroot.org/buildroot/-/issues

We are taking this opportunity to close old issues in this old
tracker. If you believe your issue is still relevant, please
open one in the new issue tracker.

Thank you!