Remove print_debug and simplify Cargo features by ludfjig · Pull Request #1980 · hyperlight-dev/hyperlight

ludfjig · 2026-10-23T18:00:15Z

Git metadata collection adds a costly build dependency and provides empty fields for crates.io builds.

Keep build metadata logging and drop git2 and Git fields.
Remove print_debug and the exported debug! macro.
Simplify Cargo feature lists.

Copilot

🟢 Approval recommended

Static review found no blocking issues, and the removals are consistent across callers, feature forwarding, build recipes, and documentation.

No open issues 🎉

What changed in this PR

This PR reduces Hyperlight host build overhead by removing two Cargo features and their logging machinery. It also simplifies feature forwarding and documents the breaking changes.

Changes:

Remove print_debug, hyperlight_host::debug!, and build-metadata logging with its build dependencies.
Simplify guest feature lists and keep common-crate tracing optional.
Update build recipes, coverage documentation, and the changelog.

File	Description
`src/tests/rust_guests/witguest/Cargo.toml`	Simplifies guest feature forwarding.
`src/tests/rust_guests/simpleguest/Cargo.toml`	Simplifies guest feature forwarding.
`src/tests/rust_guests/dummyguest/Cargo.toml`	Simplifies memory-profile forwarding.
`src/hyperlight_libc/Cargo.toml`	Removes the empty features table.
`src/hyperlight_host/src/sandbox/uninitialized.rs`	Removes build logging, uses tracing directly, and ungates tracing tests.
`src/hyperlight_host/src/sandbox/trace/context.rs`	Uses `tracing::debug!` directly.
`src/hyperlight_host/src/lib.rs`	Removes the debug macro and build-metadata machinery.
`src/hyperlight_host/Cargo.toml`	Removes both features and the `built` dependency.
`src/hyperlight_host/build.rs`	Removes metadata generation and the debug-print configuration alias.
`src/hyperlight_guest_bin/Cargo.toml`	Simplifies tracing feature forwarding.
`src/hyperlight_common/Cargo.toml`	Keeps tracing optional when enabling `std`.
`Justfile`	Removes obsolete features from checks and test commands.
`hack/clippy-package-features.sh`	Removes stale feature exclusions.
`docs/how-to-run-coverage.md`	Aligns documented feature combinations with coverage commands.
`CHANGELOG.md`	Documents feature removals and migration guidance.
`Cargo.lock`	Removes unused build-metadata dependencies.

_{Review effort: Balanced}

ludfjig · 2026-10-23T18:12:25Z

@simongdavies I know you have said in the past that build-metadata can be useful, but I don't agree. Applications can check their cargo.lock to see what version they use, and if they really want to include it in their tracing at runtime, they can do that too for any dependency they care about. I don't think hyperlight needs special feature for this

simongdavies

I don't think we should remove the build-metadata functionaility, the rest of it is fine.

simongdavies · 2026-10-26T11:12:13Z

@simongdavies I know you have said in the past that build-metadata can be useful, but I don't agree. Applications can check their cargo.lock to see what version they use, and if they really want to include it in their tracing at runtime, they can do that too for any dependency they care about. I don't think hyperlight needs special feature for this

I don't believe that we should remove build-metadata(we can remove the feature but I don't think we should remove the functionality) I don't believe that it is possible for a consumer to actually reconstruct all this information , which has the potential to be very informative useful for production incident investigation. It has extremely low run time impact, it gets emitted once when hyperlight is first initialised.

ludfjig · 2026-10-26T17:16:27Z

@simongdavies I know you have said in the past that build-metadata can be useful, but I don't agree. Applications can check their cargo.lock to see what version they use, and if they really want to include it in their tracing at runtime, they can do that too for any dependency they care about. I don't think hyperlight needs special feature for this

I don't believe that we should remove build-metadata(we can remove the feature but I don't think we should remove the functionality) I don't believe that it is possible for a consumer to actually reconstruct all this information , which has the potential to be very informative useful for production incident investigation. It has extremely low run time impact, it gets emitted once when hyperlight is first initialised.

Which information do you think is useful and do you know anybody using this? And why not let them (the applications) embed it themselves at compile time if they want, along with any other crates they care about, instead of relying on us to do it for them?

If you really want to keep this, what do you think of at least dropping the git2 dep of built so we don't need to build git all the time, since it's broken currently anyway (GIT_VERSION, GIT_DIRTY, GIT_HEAD_REF, GIT_COMMIT_HASH are not set when hyyperlight downloaded from crates.io), and I don't think anyone would need these refs during developement?

simongdavies · 2026-11-12T08:20:44Z

If you really want to keep this, what do you think of at least dropping the git2 dep of built so we don't need to build git all the time, since it's broken currently anyway (GIT_VERSION, GIT_DIRTY, GIT_HEAD_REF, GIT_COMMIT_HASH are not set when hyyperlight downloaded from crates.io), and I don't think anyone would need these refs during developement?

Yes, this sounds reasonable.

print_debug made the exported debug! macro also print to stdout in debug builds. tracing::debug! already emits the same message. The macro's cfg is evaluated in the caller's crate, so it never printed for external users. Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

* Enabling std on hyperlight-common no longer pulls in tracing. * Feature lists name only the crates each package uses directly. * Drop the empty hyperlight-libc features table and stale feature names from the clippy script. Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

ludfjig · 2026-11-12T18:00:35Z

If you really want to keep this, what do you think of at least dropping the git2 dep of built so we don't need to build git all the time, since it's broken currently anyway (GIT_VERSION, GIT_DIRTY, GIT_HEAD_REF, GIT_COMMIT_HASH are not set when hyyperlight downloaded from crates.io), and I don't think anyone would need these refs during developement?

Yes, this sounds reasonable.

Applied! Ready for another review now

hyperlight-gh-bot · 2026-11-12T18:35:03Z

Benchmark Results

Measured commit: b11097bd09c2
Baseline commit: 01df99173865

kvm / amd (Linux) (➖ stable)

No benchmark improved or regressed.

Benchmark Results

function_call_codec

	`encode_control`	`decode_vec_bytes_copy`
`byte_chunks`	`755.86 ns` (➖ 1.04x faster)
`vec_bytes`	`588.24 ns` (➖ 1.02x faster)
		`373.14 µs` (➖ 1.00x faster)

payload_allocation

	`slot_pool_segmented`
`262144`	`526.95 ns` (➖ 1.01x slower)
`65536`	`144.79 ns` (➖ 1.01x slower)

sandboxes

	`create_initialized_and_drop`
`medium`	`13.06 ms` (➖ 1.01x faster)

slot_pool

	`alloc_dealloc_128`	`alloc_dealloc_4096`	`alloc_dealloc_1500`
	`7.73 ns` (➖ 1.00x slower)	`7.72 ns` (➖ 1.00x slower)	`7.78 ns` (➖ 1.17x faster)

snapshot_files

	`load_snapshot_unverified`
`small`	`99.72 µs` (➖ 1.01x slower)

virtq_readonly

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`7.63 µs` (➖ 1.05x slower)	`7.19 µs` (➖ 1.01x slower)
`65536`	`1.93 µs` (➖ 1.08x faster)	`2.06 µs` (➖ 1.07x slower)

virtq_readwrite

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`28.23 µs` (➖ 1.04x slower)
`65536`	`6.27 µs` (➖ 1.00x slower)	`6.25 µs` (➖ 1.06x faster)
`8192`	`1.08 µs` (➖ 1.05x slower)	`1.04 µs` (➖ 1.03x slower)

kvm / intel (Linux) (➖ stable)

No benchmark improved or regressed.

Benchmark Results

function_call_codec

	`encode_control`	`decode_vec_bytes_copy`
`byte_chunks`	`811.00 ns` (➖ 1.01x slower)
`vec_bytes`	`615.93 ns` (➖ 1.01x faster)
		`744.59 µs` (➖ 1.04x faster)

payload_allocation

	`slot_pool_segmented`
`262144`	`596.89 ns` (➖ 1.02x slower)
`65536`	`202.47 ns` (➖ 1.02x slower)

sandboxes

	`create_initialized_and_drop`
`medium`	`14.92 ms` (➖ 1.00x slower)

slot_pool

	`alloc_dealloc_128`	`alloc_dealloc_4096`	`alloc_dealloc_1500`
	`8.14 ns` (➖ 1.02x slower)	`8.18 ns` (➖ 1.03x slower)	`8.26 ns` (➖ 1.04x slower)

snapshot_files

	`load_snapshot_unverified`
`small`	`62.52 µs` (➖ 1.11x slower)

virtq_readonly

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`9.04 µs` (➖ 1.02x slower)	`8.93 µs` (➖ 1.02x slower)
`65536`	`2.53 µs` (➖ 1.02x slower)	`2.53 µs` (➖ 1.01x slower)

virtq_readwrite

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`35.73 µs` (➖ 1.05x slower)
`65536`	`8.34 µs` (➖ 1.01x slower)	`8.38 µs` (➖ 1.02x slower)
`8192`	`837.09 ns` (➖ 1.00x slower)	`850.41 ns` (➖ 1.01x faster)

mshv3 / amd (Linux) (➖ stable)

No benchmark improved or regressed.

Benchmark Results

function_call_codec

	`encode_control`	`decode_vec_bytes_copy`
`byte_chunks`	`944.85 ns` (➖ 1.02x slower)
`vec_bytes`	`765.91 ns` (➖ 1.07x slower)
		`366.70 µs` (➖ 1.38x slower)

payload_allocation

	`slot_pool_segmented`
`262144`	`717.16 ns` (➖ 1.05x faster)
`65536`	`189.79 ns` (➖ 1.02x faster)

sandboxes

	`create_initialized_and_drop`
`medium`	`65.91 ms` (➖ 1.01x faster)

slot_pool

	`alloc_dealloc_128`	`alloc_dealloc_4096`	`alloc_dealloc_1500`
	`9.69 ns` (➖ 1.01x slower)	`10.02 ns` (➖ 1.02x faster)	`9.76 ns` (➖ 1.01x slower)

snapshot_files

	`load_snapshot_unverified`
`small`	`105.37 µs` (➖ 1.01x faster)

virtq_readonly

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`10.01 µs` (➖ 1.02x slower)	`10.23 µs` (➖ 1.05x faster)
`65536`	`2.24 µs` (➖ 1.00x slower)	`2.43 µs` (➖ 1.01x faster)

virtq_readwrite

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`36.40 µs` (➖ 1.06x faster)
`65536`	`8.52 µs` (➖ 1.24x faster)	`8.46 µs` (➖ 1.16x faster)
`8192`	`1.26 µs` (➖ 1.04x slower)	`1.26 µs` (➖ 1.02x faster)

mshv3 / intel (Linux) (➖ stable)

No benchmark improved or regressed.

Benchmark Results

function_call_codec

	`encode_control`	`decode_vec_bytes_copy`
`byte_chunks`	`928.21 ns` (➖ 1.03x faster)
`vec_bytes`	`673.71 ns` (➖ 1.02x slower)
		`676.88 µs` (➖ 1.01x slower)

payload_allocation

	`slot_pool_segmented`
`262144`	`627.30 ns` (➖ 1.06x faster)
`65536`	`236.96 ns` (➖ 1.08x faster)

sandboxes

	`create_initialized_and_drop`
`medium`	`60.66 ms` (➖ 1.24x faster)

slot_pool

	`alloc_dealloc_128`	`alloc_dealloc_4096`	`alloc_dealloc_1500`
	`9.16 ns` (➖ 1.05x slower)	`9.17 ns` (➖ 1.04x slower)	`9.13 ns` (➖ 1.05x slower)

snapshot_files

	`load_snapshot_unverified`
`small`	`56.79 µs` (➖ 1.04x slower)

virtq_readonly

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`8.02 µs` (➖ 1.01x slower)	`7.97 µs` (➖ 1.00x faster)
`65536`	`2.28 µs` (➖ 1.00x slower)	`2.28 µs` (➖ 1.01x faster)

virtq_readwrite

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`41.43 µs` (➖ 1.09x slower)
`65536`	`7.54 µs` (➖ 1.00x slower)	`7.53 µs` (➖ 1.01x faster)
`8192`	`896.68 ns` (➖ 1.03x faster)	`893.79 ns` (➖ 1.03x faster)

hyperv-ws2025 / amd (Windows) (➖ stable)

No benchmark improved or regressed.

Benchmark Results

function_call_codec

	`encode_control`	`decode_vec_bytes_copy`
`byte_chunks`	`1.16 µs` (➖ 1.08x faster)
`vec_bytes`	`781.59 ns` (➖ 1.14x faster)
		`2.20 ms` (➖ 1.01x slower)

payload_allocation

	`slot_pool_segmented`
`262144`	`795.10 ns` (➖ 1.00x slower)
`65536`	`230.76 ns` (➖ 1.00x faster)

sandboxes

	`create_initialized_and_drop`
`medium`	`12.71 ms` (➖ 1.03x faster)

slot_pool

	`alloc_dealloc_128`	`alloc_dealloc_4096`	`alloc_dealloc_1500`
	`10.60 ns` (➖ 1.00x faster)	`10.59 ns` (➖ 1.00x faster)	`10.61 ns` (➖ 1.00x slower)

snapshot_files

	`load_snapshot_unverified`
`small`	`794.23 µs` (➖ 1.01x faster)

virtq_readonly

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`8.67 µs` (➖ 1.01x faster)	`8.63 µs` (➖ 1.05x faster)
`65536`	`2.54 µs` (➖ 1.01x faster)	`2.52 µs` (➖ 1.03x faster)

virtq_readwrite

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`37.52 µs` (➖ 1.04x faster)
`65536`	`8.57 µs` (➖ 1.05x faster)	`8.88 µs` (➖ 1.02x slower)
`8192`	`1.34 µs` (➖ 1.02x faster)	`1.38 µs` (➖ 1.04x slower)

hyperv-ws2025 / intel (Windows) (➖ stable)

No benchmark improved or regressed.

Benchmark Results

function_call_codec

	`encode_control`	`decode_vec_bytes_copy`
`byte_chunks`	`1.25 µs` (➖ 1.01x faster)
`vec_bytes`	`834.65 ns` (➖ 1.05x slower)
		`3.09 ms` (➖ 1.04x slower)

payload_allocation

	`slot_pool_segmented`
`262144`	`745.23 ns` (➖ 1.00x slower)
`65536`	`208.89 ns` (➖ 1.00x faster)

sandboxes

	`create_initialized_and_drop`
`medium`	`14.42 ms` (➖ 1.03x slower)

slot_pool

	`alloc_dealloc_128`	`alloc_dealloc_4096`	`alloc_dealloc_1500`
	`9.74 ns` (➖ 1.03x faster)	`10.06 ns` (➖ 1.02x slower)	`9.64 ns` (➖ 1.10x faster)

snapshot_files

	`load_snapshot_unverified`
`small`	`676.59 µs` (➖ 1.01x faster)

virtq_readonly

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`7.73 µs` (➖ 1.00x faster)	`7.48 µs` (➖ 1.03x faster)
`65536`	`2.34 µs` (➖ 1.00x faster)	`2.30 µs` (➖ 1.01x faster)

virtq_readwrite

	`slot_pool_segmented`	`slot_pool_segmented_fragmented`
`262144`	`41.15 µs` (➖ 1.02x faster)
`65536`	`8.50 µs` (➖ 1.01x slower)	`8.66 µs` (➖ 1.03x slower)
`8192`	`1.08 µs` (➖ 1.08x faster)	`1.11 µs` (➖ 1.04x slower)

_{Reported by cargo ci bench-report --candidate run:43269815474 --config-file bench_report.toml.}

Copilot AI balanced review requested due to automatic review settings October 23, 2026 18:00

ludfjig requested a review from danbugs as a code owner October 23, 2026 18:00

ludfjig added the C-refactor For PRs that restructure or remove code without adding new functionality. label Oct 23, 2026

ludfjig requested review from andreiltd, dblnz, devigned, jprendes, jsturtevant, simongdavies, squillace and syntactically as code owners October 23, 2026 18:00

Copilot started reviewing on behalf of ludfjig October 23, 2026 18:10

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ludfjig and others added 3 commits November 12, 2026 09:21

Drop Git metadata collection from build-metadata

b11097b

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

ludfjig dismissed andreiltd’s stale review via b11097b November 12, 2026 17:28

ludfjig force-pushed the remove-print-debug-build-metadata branch from 7a74694 to b11097b Compare November 12, 2026 17:28

ludfjig changed the title ~~Remove the print_debug and build-metadata cargo features~~ Remove print_debug and simplify Cargo features Nov 12, 2026

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Benchmark Results

Benchmark Results

function_call_codec

payload_allocation

sandboxes

slot_pool

snapshot_files

virtq_readonly

virtq_readwrite

Benchmark Results

function_call_codec

payload_allocation

sandboxes

slot_pool

snapshot_files

virtq_readonly

virtq_readwrite

Benchmark Results

function_call_codec

payload_allocation

sandboxes

slot_pool

snapshot_files

virtq_readonly

virtq_readwrite

Benchmark Results

function_call_codec

payload_allocation

sandboxes

slot_pool

snapshot_files

virtq_readonly

virtq_readwrite

Benchmark Results

function_call_codec

payload_allocation

sandboxes

slot_pool

snapshot_files

virtq_readonly

virtq_readwrite

Benchmark Results

function_call_codec

payload_allocation

sandboxes

slot_pool

snapshot_files

virtq_readonly

virtq_readwrite

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