build(deps): only enable used nightly features for the x86_64 crate

[mkroening]

The x86_64 crate provides a nightly feature, which enables the const_fn, step_trait, abi_x86_interrupt, and asm_const features. The step_trait was changed backwards-incompatibly in a recent nightly Rust version.

This PR disables unused nightly features of the x86_64 crate to reduce the number of nightly changes breaking compilation for us.

This PR should unblock the following two PRs:

• build(deps): Bump x86_64 from 0.15.4 to 0.15.5 #2551
• build(deps): Bump rust-toolchain from nightly-2026-07-01 to nightly-2026-07-20 #2553

[github-actions]

Benchmark Results

Details

Benchmark	Current: 528235c	Previous: 2e23902	Performance Ratio
startup_benchmark Build Time	90.96 s	80.34 s	1.13 ❗
startup_benchmark File Size	0.80 MB	0.80 MB	1.00 ❗
Startup Time - 1 core	0.73 s (±0.02 s)	0.75 s (±0.02 s)	0.98
Startup Time - 2 cores	0.74 s (±0.02 s)	0.74 s (±0.02 s)	1.00
Startup Time - 4 cores	0.75 s (±0.03 s)	0.74 s (±0.02 s)	1.01
multithreaded_benchmark Build Time	83.77 s	82.11 s	1.02 ❗
multithreaded_benchmark File Size	0.86 MB	0.86 MB	1.00 ❗
Multithreaded Pi Efficiency - 2 Threads	88.03 % (±5.96 %)	85.89 % (±6.61 %)	1.02
Multithreaded Pi Efficiency - 4 Threads	43.94 % (±2.00 %)	43.43 % (±2.56 %)	1.01
Multithreaded Pi Efficiency - 8 Threads	25.34 % (±1.36 %)	25.76 % (±1.53 %)	0.98
micro_benchmarks Build Time	95.51 s	80.40 s	1.19 ❗
micro_benchmarks File Size	0.86 MB	0.86 MB	1.00 ❗
Scheduling time - 1 thread	62.59 ticks (±2.27 ticks)	62.65 ticks (±4.06 ticks)	1.00
Scheduling time - 2 threads	35.30 ticks (±5.12 ticks)	34.08 ticks (±4.10 ticks)	1.04
Micro - Time for syscall (getpid)	4.28 ticks (±0.77 ticks)	3.45 ticks (±0.58 ticks)	1.24
Memcpy speed - (built_in) block size 4096	80924.18 MByte/s (±56127.55 MByte/s)	82448.38 MByte/s (±56997.13 MByte/s)	0.98
Memcpy speed - (built_in) block size 1048576	30607.51 MByte/s (±24728.29 MByte/s)	30585.98 MByte/s (±24707.84 MByte/s)	1.00
Memcpy speed - (built_in) block size 16777216	27669.27 MByte/s (±22869.67 MByte/s)	26340.06 MByte/s (±21720.96 MByte/s)	1.05
Memset speed - (built_in) block size 4096	81411.64 MByte/s (±56446.36 MByte/s)	82292.76 MByte/s (±56891.50 MByte/s)	0.99
Memset speed - (built_in) block size 1048576	31332.20 MByte/s (±25144.15 MByte/s)	31323.85 MByte/s (±25145.86 MByte/s)	1.00
Memset speed - (built_in) block size 16777216	28437.56 MByte/s (±23338.86 MByte/s)	27104.68 MByte/s (±22209.94 MByte/s)	1.05
Memcpy speed - (rust) block size 4096	74669.87 MByte/s (±51935.42 MByte/s)	74097.96 MByte/s (±51811.44 MByte/s)	1.01
Memcpy speed - (rust) block size 1048576	30495.83 MByte/s (±24721.36 MByte/s)	30361.60 MByte/s (±24602.37 MByte/s)	1.00
Memcpy speed - (rust) block size 16777216	26645.98 MByte/s (±22095.77 MByte/s)	27625.34 MByte/s (±22806.88 MByte/s)	0.96
Memset speed - (rust) block size 4096	75179.29 MByte/s (±52309.30 MByte/s)	74373.47 MByte/s (±51976.48 MByte/s)	1.01
Memset speed - (rust) block size 1048576	31236.26 MByte/s (±25151.75 MByte/s)	31110.89 MByte/s (±25033.24 MByte/s)	1.00
Memset speed - (rust) block size 16777216	27411.43 MByte/s (±22579.57 MByte/s)	28386.93 MByte/s (±23265.03 MByte/s)	0.97
alloc_benchmarks Build Time	75.46 s	74.76 s	1.01 ❗
alloc_benchmarks File Size	0.87 MB	0.87 MB	1.00 ❗
Allocations - Allocation success	91.31 %	91.31 %	1
Allocations - Deallocation success	100.00 %	100.00 %	1
Allocations - Pre-fail Allocations	61.44 %	61.44 %	1
Allocations - Average Allocation time	2824.10 Ticks (±1104.04 Ticks)	5860.58 Ticks (±98.43 Ticks)	0.48 ❗
Allocations - Average Allocation time (no fail)	3895.72 Ticks (±1024.25 Ticks)	6554.81 Ticks (±92.86 Ticks)	0.59 ❗
Allocations - Average Deallocation time	786.12 Ticks (±276.47 Ticks)	1805.01 Ticks (±250.35 Ticks)	0.44 ❗
mutex_benchmark Build Time	81.40 s	79.82 s	1.02 ❗
mutex_benchmark File Size	0.86 MB	0.86 MB	1.00 ❗
Mutex Stress Test Average Time per Iteration - 1 Threads	12.04 ns (±0.28 ns)	12.10 ns (±0.41 ns)	1.00
Mutex Stress Test Average Time per Iteration - 2 Threads	39.06 ns (±2.42 ns)	40.26 ns (±1.68 ns)	0.97

This comment was automatically generated by workflow using github-action-benchmark.