id = 456
title = "Qemu User (x86_64) Hangs after futex function not implemented error"
state = "closed"
created_at = "2021-06-29T20:52:22.321Z"
closed_at = "2023-01-18T01:23:41.722Z"
labels = ["Closed::Fixed", "linux-user"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/456"
host-os = "Ubuntu 21.04 (Raspberry Pi 4 8GB RAM)"
host-arch = "aarch64"
qemu-version = "qemu-x86_64 version 5.2.0 (Debian 1:5.2+dfsg-9ubuntu3)"
guest-os = "n/a"
guest-arch = "n/a"
description = """Qemu User hangs on futex call with the following last strace
```
futex(0x0000004001a01654,FUTEX_PRIVATE_FLAG|FUTEX_UNLOCK_PI,0,NULL,NULL,0) = -1 errno=38 (Function not implemented)
```
This is the last call until giving a SIGINT with CTRL + C where the following strace is output
```
futex(0x00000040b0085180,FUTEX_PRIVATE_FLAG|FUTEX_WAIT,2,NULL,NULL,0) = -1 errno=4 (Interrupted system call)
--- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL, si_pid=0, si_uid=0} ---

```"""
reproduce = """1. Install steamcmd https://developer.valvesoftware.com/wiki/SteamCMD
2. In the steamcmd shell install Valheim dedicated server with `app_update 896660`
3. Navigate to the downloaded app `cd ~/Steam/steamapps/common/Valheim\\ dedicated\\ server/`
4. Run `qemu-x86_64 valheim_server.x86_64`
5. The process hangs as per description."""
additional = """The issue was originally encountered on a raspberry pi ARM64 host using the ubuntu 5.2.0 version of qemu. Installed cross libararies:
* libc6-amd64-cross
* libgcc-s1-amd64-cross

It was then replicated on the x86 host fedora with a build of the qemu master branch.
The full qemu -strace output is provided below
[qemu_strace_output.log](/uploads/96e0e31b1e63191a94d73f05023c5173/qemu_strace_output.log)

The expected output found when running `strace ./valheim_server.x86_64` without qemu on the x86_64 host is attached below
[expected_output.log](/uploads/b3b25618103de8a3b9c0ef227bbffc9c/expected_output.log)"""