rio::new fails with "Function not implemented"

[Heinz N. Gies]

Running cargo test leads to:

thread 'test_vec_value' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 38, kind: Other, message: "Function not implemented" }', src/libcore/result.rs:1188:5
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:84
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:61
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1025
   5: std::io::Write::write_fmt
             at /rustc/5e1a799842ba6ed4a57e91f7ab9435947482f7d8/src/libstd/io/mod.rs:1426
   6: std::io::impls::<impl std::io::Write for alloc::boxed::Box<W>>::write_fmt
             at src/libstd/io/impls.rs:156
   7: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:65
   8: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:50
   9: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:193
  10: std::panicking::default_hook
             at src/libstd/panicking.rs:207
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:471
  12: rust_begin_unwind
             at src/libstd/panicking.rs:375
  13: core::panicking::panic_fmt
             at src/libcore/panicking.rs:84
  14: core::result::unwrap_failed
             at src/libcore/result.rs:1188
  15: core::result::Result<T,E>::unwrap
             at /rustc/5e1a799842ba6ed4a57e91f7ab9435947482f7d8/src/libcore/result.rs:956
  16: vec::test_vec_value
             at tests/vec.rs:12
  17: vec::test_vec_value::{{closure}}
             at tests/vec.rs:4
  18: core::ops::function::FnOnce::call_once
             at /rustc/5e1a799842ba6ed4a57e91f7ab9435947482f7d8/src/libcore/ops/function.rs:232
  19: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/5e1a799842ba6ed4a57e91f7ab9435947482f7d8/src/liballoc/boxed.rs:1022
  20: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:78
  21: std::panicking::try
             at /rustc/5e1a799842ba6ed4a57e91f7ab9435947482f7d8/src/libstd/panicking.rs:270
  22: std::panic::catch_unwind
             at /rustc/5e1a799842ba6ed4a57e91f7ab9435947482f7d8/src/libstd/panic.rs:394
  23: test::run_test_in_process
             at src/libtest/lib.rs:567
  24: test::run_test::run_test_inner::{{closure}}
             at src/libtest/lib.rs:474
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

running on:

➜  rio uname -a
Linux benchy 4.18.0-147.3.1.el8_1.x86_64 #1 SMP Fri Jan 3 23:55:26 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
➜  rio rustc --version
rustc 1.41.0 (5e1a79984 2020-01-27)

[Simon Eskildsen]

Ah, your kernel version is too out of date. You need to be on 5.1, minimum, for io_uring. The kernel literally doesn't have the syscall implemented

[Heinz N. Gies]

😢 that explains it!

[Heinz N. Gies]

Closing this as this explains it.