Your system information

• Steam client version: 1776387948 / April 15th 2026
• Distribution: Ubuntu Noble, Fedora 42 (Independent of distro)
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes
• GPU: Nvidia Tegra X1 (Nintendo Switch)
• CPU: ARM Cortex-A57

Please describe your issue in as much detail as possible:

I know the native Steam ARM64 client has not been released officially, but I have been running it for a while now. However, client builds newer than April 15th (1776387948) immediately crash with an illegal instruction error.

After some debugging, it appears that the hardware requirements for the native client have been raised to target Armv8.1 with LSE. Because the Cortex-A57 lacks these atomic instructions, it throws a SIGILL fault. I was wondering if the removal of the Armv8.0 fallback (likely compiled with -moutline-atomics before) was intentional or if there are any plans to restore Armv8.0 support at some point.

GDB Backtrace from the steam binary in ~/steam/steamrtarm64/:

Program received signal SIGILL, Illegal instruction.
0x00000055556358c0 in ?? ()
(gdb) disas $pc-32,+64
Dump of assembler code from 0x55556358a0 to 0x55556358e0:
   0x00000055556358a0:  mov     x2, #0x1                        // #1
   0x00000055556358a4:  ldaddal x2, x0, [x0]
   0x00000055556358a8:  ret
   0x00000055556358ac:  nop
   0x00000055556358b0:  mov     x2, #0xffffffffffffffff         // #-1
   0x00000055556358b4:  ldaddal x2, x0, [x0]
   0x00000055556358b8:  ret
   0x00000055556358bc:  nop
=> 0x00000055556358c0:  ldaddal x1, x0, [x0]
   0x00000055556358c4:  ret
   0x00000055556358c8:  swpa    x1, x0, [x0]
   0x00000055556358cc:  ret
   0x00000055556358d0:  mov     x3, x0
   0x00000055556358d4:  mov     x0, x2
   0x00000055556358d8:  casal   x0, x1, [x3]
   0x00000055556358dc:  ret
End of assembler dump.

Steps for reproducing this issue:

1. Run any native ARM64 Steam client build newer than April 15th, 2026, on an Armv8.0 CPU
2. The client will immediately crash on startup with SIGILL.