Public bug reported: [ Impact ]
* Qemu 8.2.2 reports support for the riscv64 vector instruction, but fails to set the emulated vstart_eq_zero flag, which then causes illegal instruction crashes in certain cases. * Launchpad builders use the same Qemu package as noble, so fixing this in Noble will also be basis for fixing our riscv64 builds which use vector instructions. * This was reported upstream (https://gitlab.com/qemu-project/qemu/-/issues/1976) and fixed in 9.0, so please backport the fix linked in the issue. [ Test Plan ] * I've attached some code which can reproduce the issue. * Reproduction requires running a riscv64 Noble image via Qemu system emulation on an amd64 host, as described in https://wiki.ubuntu.com/RISC-V/QEMU * Boot up the VM, transfer the necessary files over, `apt install build-essential unzip`, then unzip the reproduction files and compile & run the test (within the VM) with `make`. [ Where problems could occur ] * All changes are restricted to target/riscv in the Qemu tree, so no changes are expected in other architectures. Furthermore, they should only affect vector instructions. * Possible problems range from build failures to riscv emulation failing completely, but the test above covers those cases. [ Other Info ] * n/a ** Affects: qemu (Ubuntu) Importance: Undecided Status: New ** Affects: qemu (Ubuntu Noble) Importance: Undecided Assignee: Gabriel B. Sant'Anna (baioc) Status: New ** Attachment added: "Minimal example to reproduce the issue" https://bugs.launchpad.net/bugs/2095169/+attachment/5852451/+files/repro.zip -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2095169 Title: [SRU] SIGILL on emulation of RISC-V Vector instructions To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2095169/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
