Arch Linux

orlfman

Member

Registered: 2007-11-20

Posts: 145

[solved]is futex2 enabled by default in arch 5.16?

linux 5.16 brings futex2 support and issuing a:

sudo dmesg | grep futex

nets me the following results:

[    0.421292] futex hash table entries: 8192 (order: 7, 524288 bytes, linear)

it's not listing back futex2. only futex "1." is futex2 not enabled by default with the offical arch 5.16 kernel? this is my uname:

Linux linux64 5.16.5-arch1-1 #1 SMP PREEMPT Tue, 01 Feb 2022 21:42:50 +0000 x86_64 GNU/Linux

edit:
i don't think it is... i grabed https://github.com/weirddan455/futex-test to run a test to see if it is enabled. its reporting back:

Kernel name: Linux
Kernel version 5.16.5-arch1-1
Linux kernel detected
futex-FUTEX_WAIT_MULTIPLE: Function not implemented
futex-FUTEX_WAIT_MULTIPLE: Function not implemented
FUTEX_WAIT_MULTIPLE test failed
access /sys/kernel/futex2: No such file or directory
futex2 test failed
Mainline (kernel 5.16+) futex2 test successful

Last edited by orlfman (2022-02-06 21:19:49)

loqs

Member

Registered: 2014-03-06

Posts: 18,899

Re: [solved]is futex2 enabled by default in arch 5.16?

https://github.com/weirddan455/futex-test/issues/2

orlfman

Member

Registered: 2007-11-20

Posts: 145

Re: [solved]is futex2 enabled by default in arch 5.16?

https://github.com/weirddan455/futex-test/issues/2

oh that's interesting. so with 5.16 is futex2 under the regular futex umbrella term when searching with sudo dmesg | grep futex?
edit:
futex2 is now just reported as futex in dmesg in 5.16 and the testers use to check for the old patches and the keypart, Mainline (kernel 5.16+) futex2 test successful, means futex2 is enabled in the kernel. never mind my panic post.

Last edited by orlfman (2022-02-06 21:21:04)

loqs

Member

Registered: 2014-03-06

Posts: 18,899

Re: [solved]is futex2 enabled by default in arch 5.16?

The new system call is futex_waitv
https://git.kernel.org/pub/scm/linux/ke … 1d4e22b4d1
https://git.kernel.org/pub/scm/linux/ke … f85b5ed3d9
https://git.kernel.org/pub/scm/linux/ke … 299b28ca49

glibc 2.35 will support it when built with 5.16 headers.  I suspect wine / proton have not been updated to support futex_waitv yet.

Last edited by loqs (2022-02-10 06:03:49)