Regression from 2408 to 2409 (segfault on running anything)

[theofficialgman]

Device:

OS: Ubuntu noble 24.04 aarch64
Host: Nintendo Switch (2017)
Kernel: Linux 4.9.140-l4t
Uptime: 1 hour, 18 mins
Packages: 3276 (dpkg), 6 (flatpak)
Shell: bash 5.2.21
DE: KDE Plasma 5.27.11
WM: KWin (X11)
WM Theme: Breeze
Theme: Breeze (Light) [Qt], Breeze [GTK2/3/4]
Icons: Breeze [Qt], breeze-dark [GTK2/3/4]
Font: Noto Sans (10pt) [Qt], Noto Sans (10pt) [GTK2/3/4]
Cursor: Breeze (24px)
Terminal: /dev/pts/3
CPU: icosa (4) @ 2.09 GHz
GPU: NVIDIA Tegra X1 (nvgpu) [Integrated]
Memory: 1.70 GiB / 3.90 GiB (44%)
Swap: 0 B / 3.00 GiB (0%)
Disk (/): 59.42 GiB / 122.94 GiB (48%) - ext4
Battery: 100% [AC Connected]
Locale: C.UTF-8

Starting with 2409 (build from source or the Ubuntu PPA) I get the following error on running any command (such as FEXBash)

Illegal instruction (core dumped)

This is not an issue on 2408 or previous versions in my testing.

Happy to bisect further if any developer has insight in which change likely could be the cause of this issue

my build (release) only gives the following in gdb bt

#0  0x000000555576c904 in FEX::FetchHostFeatures() ()
#1  0x0000005555630dec in main ()

so maybe it has something to do with 941b065 which was introduced in 2409?

CC: @Azkali @bylaws

[Sonicadvance1]

This is due to your kernel being too old to handle ARM's "cpuid" emulation. This change happened with #3962
Theoretically our minimum spec of Linux 5.0 should support all the feature registers we query.

[theofficialgman]

Gotcha, so the changes that were added in kernel 4.11 for arm64 HWCAP_CPUID are now required (as documented here torvalds/linux@4aa8a47 and added here torvalds/linux@77c97b4). Probably more after that but that is the gist of it.

[AndreRH]

This is due to your kernel being too old to handle ARM's "cpuid" emulation. This change happened with #3962
Theoretically our minimum spec of Linux 5.0 should support all the feature registers we query.

What about catching the exception and then assuming no features to be present? Things would run slower, but better than not at all