[Buildroot] Weird issue with uClibc RISC-V 32-bit in Qemu

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello,

I am working on updating the toolchains of toolchains.bootlin.com, and
as part of that rebuilding all toolchains with Buildroot 2024.05 + a
few patches:

  https://github.com/bootlin/buildroot-toolchains/tree/toolchains.bootlin.com-2024.05

On riscv32-ilp32d, I have the uClibc stable toolchain that generates a
system that doesn't boot under Qemu: the kernel boots fine, but when
switching to user-space, nothing happens:

  https://gitlab.com/buildroot.org/toolchains-builder/-/jobs/7378190992

The interesting thing is that the uClibc bleeding-edge toolchain works
fine. The only difference is that GCC is 14.x instead of 13.x, and
binutils is 2.42 instead of 2.41. Bleeding edge toolchain:

  https://gitlab.com/buildroot.org/toolchains-builder/-/jobs/7378190991

I took just the rootfs.ext2 of the "working" build, and put it together
with the firmware+kernel of the "non working" build, and it works fine:
so the problem is in the rootfs.

In the broken build, if I pass init=/bin/sh, then I'm dropped into a
shell, but some things are weird:

 - When I run ls, the first line of output starts right after the
   prompt, not in a newline

 - After ls has finished, it doesn't got back to the shell prompt,
   unless I press Enter again

Using init=/bin/sh with the fully working rootfs does not exhibit this
issue.

You can retrieve the non-working artefacts and defconfig at:

  https://gitlab.com/buildroot.org/toolchains-builder/-/jobs/7378190992/artifacts/browse/test/output/

And the working artefact and defconfig at:

  https://gitlab.com/buildroot.org/toolchains-builder/-/jobs/7378190991/artifacts/browse/test/output/

Do you have any clue at what could be happening here?

Thanks for your support!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot