Remove i686-guest, nanvix-unstable and guest-counter features

Removes the experimental 32-bit i686 guest support along with the
nanvix-unstable and guest-counter cargo features that depended on or
accompanied it. This deletes the i686 arch modules, the PEB file-mapping
plumbing (labels, preallocated FileMappingInfo array), the GuestCounter
API, and the associated cfg gating, tests, Justfile recipes, CI matrix
entries and docs.

As part of the cleanup, the ReadableSharedMemory trait machinery in
mem::layout is now gated on a precise 'readable_shared_mem' cfg alias
(gdb debug path or shared-snapshot mem_profile path) instead of a blanket

Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>
#[allow(unused)], so it is compiled out entirely when unused.

Author: simongdavies

.github/workflows/dep_code_checks.yml

@@ -82,11 +82,6 @@ jobs:
       - name: Verify MSRV
         run: ./dev/verify-msrv.sh hyperlight-host hyperlight-guest hyperlight-guest-bin hyperlight-common
 
-      - name: Check 32-bit builds (Nanvix compatibility)
-        run: |
-          rustup target add i686-unknown-linux-gnu
-          just check-i686 debug
-
       - name: Check cargo features compile
         run: just check
 

CHANGELOG.md

@@ -4,6 +4,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Prerelease] - Unreleased
 
+### Removed
+* Removed the experimental `i686-guest`, `nanvix-unstable`, and `guest-counter` feature flags, along with 32-bit (i686) guest support and its page-table/snapshot code paths. Hyperlight guests are now 64-bit only (x86_64 and aarch64).
+
 ## [v0.15.0] - 2026-05-06
 
 ### Added

Justfile

@@ -124,9 +124,6 @@ code-checks-like-ci config=default-target hypervisor="kvm":
     @# Verify MSRV
     ./dev/verify-msrv.sh hyperlight-common hyperlight-guest hyperlight-guest-bin hyperlight-host hyperlight-component-util hyperlight-component-macro hyperlight-guest-tracing
 
-    @# Check 32-bit guests
-    {{ if os() == "linux" { "just check-i686 " + config } else { "" } }}
-
     @# Check cargo features compile
     just check
 
@@ -265,14 +262,6 @@ test-rust-tracing target=default-target features="":
     {{ cargo-cmd }} test -p hyperlight-common -F trace_guest --profile={{ if target == "debug" { "dev" } else { target } }} {{ target-triple-flag }}
     {{ cargo-cmd }} test -p hyperlight-host --profile={{ if target == "debug" { "dev" } else { target } }} {{ if features =="" {'--features trace_guest'} else { "--features trace_guest," + features } }} {{ target-triple-flag }}
 
-# verify hyperlight-common and hyperlight-guest build for 32-bit (for Nanvix compatibility - uses i686 as proxy for Nanvix's custom 32-bit x86 target)
-check-i686 target=default-target:
-    cargo check -p hyperlight-common --target i686-unknown-linux-gnu --profile={{ if target == "debug" { "dev" } else { target } }}
-    cargo check -p hyperlight-guest --target i686-unknown-linux-gnu --profile={{ if target == "debug" { "dev" } else { target } }}
-    cargo check -p hyperlight-common --target i686-unknown-linux-gnu --features i686-guest --profile={{ if target == "debug" { "dev" } else { target } }}
-    # Verify that trace_guest correctly fails on i686 (compile_error should trigger)
-    ! cargo check -p hyperlight-guest --target i686-unknown-linux-gnu --features trace_guest --profile={{ if target == "debug" { "dev" } else { target } }} 2>/dev/null
-
 test-doc target=default-target features="":
     {{ cargo-cmd }} test --profile={{ if target == "debug" { "dev" } else { target } }} {{ target-triple-flag }} {{ if features =="" {''} else { "--features " + features } }} --doc
 
@@ -292,9 +281,8 @@ check:
     {{ cargo-cmd }} check -p hyperlight-host --features print_debug  {{ target-triple-flag }}
     {{ cargo-cmd }} check -p hyperlight-host --features gdb  {{ target-triple-flag }}
     {{ cargo-cmd }} check -p hyperlight-host --features trace_guest,mem_profile  {{ target-triple-flag }}
-    {{ cargo-cmd }} check -p hyperlight-host --features i686-guest  {{ target-triple-flag }}
-    {{ cargo-cmd }} check -p hyperlight-host --features i686-guest,executable_heap  {{ target-triple-flag }}
     {{ cargo-cmd }} check -p hyperlight-host --features hw-interrupts  {{ target-triple-flag }}
+    {{ cargo-cmd }} check -p hyperlight-host --features executable_heap  {{ target-triple-flag }}
 
 fmt-check: (ensure-nightly-fmt)
     cargo +{{nightly-toolchain}} fmt --all -- --check

flake.nix

@@ -82,7 +82,6 @@
                 "x86_64-unknown-linux-gnu"
                 "x86_64-pc-windows-msvc" "x86_64-unknown-none"
                 "wasm32-wasip1" "wasm32-wasip2" "wasm32-unknown-unknown"
-                "i686-unknown-linux-gnu"
               ];
               extensions = [ "rust-src" ] ++ (if args.channel == "nightly" then [ "miri-preview" ] else []);
             });

src/hyperlight_common/Cargo.toml

@@ -34,9 +34,6 @@ fuzzing = ["dep:arbitrary"]
 trace_guest = []
 mem_profile = []
 std = ["thiserror/std", "log/std", "tracing/std"]
-i686-guest = []
-nanvix-unstable = ["i686-guest"]
-guest-counter = []
 
 [dev-dependencies]
 quickcheck = "1.0.3"

src/hyperlight_common/src/arch/amd64/vmem.rs

@@ -333,10 +333,6 @@ unsafe fn map_page<
 /// independently and emits all leaves as `ThisSpace`. Aliased
 /// intermediate-table detection is not implemented here because no
 /// current embedder exercises that pattern on amd64.
-///
-/// TODO: align with the i686 implementation and detect aliased
-/// intermediate tables to avoid semantic divergence across arches.
-/// Tracking: follow-up issue.
 #[allow(clippy::missing_safety_doc)]
 pub unsafe fn walk_va_spaces<Op: TableReadOps>(
     op: &Op,