M7 Phase 2: Global /proc File Validation

Phase 2 validates the 10 global /proc files that were implemented during M5 and enriches /proc/cpuinfo with CPUID-derived fields that userspace tools expect.

What already existed

All 10 system-wide /proc files were implemented during M5 Phase 4: cpuinfo, version, meminfo, mounts, stat, uptime, loadavg, filesystems, cmdline, and metrics. They serve live data from the page allocator, process table, mount table, and TSC clock. Phase 2's job was to verify format correctness and fill gaps.

cpuinfo enrichment

The existing /proc/cpuinfo had processor, vendor_id, model name, MHz, cache size, flags, and bogomips — but was missing cpu family, model, and stepping. These three fields are parsed by lscpu, Python's platform.processor(), and glibc's CPU feature detection.

The fix adds a cpuid_family_model_stepping() function to the platform crate that reads CPUID leaf 1 via the raw-cpuid crate:

#![allow(unused)]
fn main() {
pub fn cpuid_family_model_stepping() -> (u32, u32, u32) {
    let info = CpuId::new().get_feature_info().unwrap();
    (info.family_id() as u32, info.model_id() as u32, info.stepping_id() as u32)
}
}

The raw-cpuid crate handles the Intel/AMD extended family/model encoding automatically — family_id() combines base and extended family for families >= 15, and model_id() combines base and extended model for families 6 and 15.

Contract test

The new proc_global.c contract test verifies all six key global files:

  • /proc/cpuinfo — contains processor field
  • /proc/version — contains kernel name substring
  • /proc/meminfo — MemTotal: with value > 0
  • /proc/mounts — at least one mount entry
  • /proc/uptime — two parseable floats > 0
  • /proc/loadavg — five parseable fields (three averages + running/total)

Results

21/21 contract tests pass, including the new proc_global test.

What's next

Phase 3 enriches the per-process /proc files. The existing /proc/[pid]/stat outputs 52 fields but many are hardcoded zeros. Phase 3 adds real values for utime/stime (CPU accounting), num_threads, starttime, vsize, and rss — the fields that ps, top, and htop actually parse.