Stream: git-wasmtime

Topic: wasmtime / Issue #2294 Modules built from Rust only work ...

Wasmtime GitHub notifications bot (Oct 16 2020 at 00:18):

itowlson opened Issue #2294:

When I write a program in Rust and compile it to WASM, I cannot run it under wasmtime on Windows unless I passed the --release flag when I built it. If I built the WASM module in debug mode, wasmtime gives the error "command export '__rustc_debug_gdb_scripts_section__' is not a function". All other combinations of OS and build mode work: the error is specific to debug builds under Windows.

Steps to reproduce

1. Get hold of a Windows box. Install Rust, the wasm32-wasi target and wasmtime.
2. cargo new a hello-world program.
3. cd into the hello-world directory and cargo build --target wasm32-wasi
4. Run wasmtime run .\target\wasm32-wasi\debug\hello-world.wasm

Results

Expected: Should print Hello, world!

Actual:

Error: failed to run main module `.\target\wasm32-wasi\debug\hello-world.wasm`

Caused by:
    0: failed to instantiate ".\\target\\wasm32-wasi\\debug\\hello-world.wasm"
    1: command export '__rustc_debug_gdb_scripts_section__' is not a function

Environment

Windows 10, x64
Rust 1.40.0
Wasmtime 0.20.0

Additional information

• If I cargo build ... --release and use wasmtime to run the release build, it works.
• If I run the debug build on Linux (WSL Ubuntu), it works.

Wasmtime GitHub notifications bot (Oct 16 2020 at 00:18):

itowlson labeled Issue #2294:

When I write a program in Rust and compile it to WASM, I cannot run it under wasmtime on Windows unless I passed the --release flag when I built it. If I built the WASM module in debug mode, wasmtime gives the error "command export '__rustc_debug_gdb_scripts_section__' is not a function". All other combinations of OS and build mode work: the error is specific to debug builds under Windows.

Steps to reproduce

1. Get hold of a Windows box. Install Rust, the wasm32-wasi target and wasmtime.
2. cargo new a hello-world program.
3. cd into the hello-world directory and cargo build --target wasm32-wasi
4. Run wasmtime run .\target\wasm32-wasi\debug\hello-world.wasm

Results

Expected: Should print Hello, world!

Actual:

Error: failed to run main module `.\target\wasm32-wasi\debug\hello-world.wasm`

Caused by:
    0: failed to instantiate ".\\target\\wasm32-wasi\\debug\\hello-world.wasm"
    1: command export '__rustc_debug_gdb_scripts_section__' is not a function

Environment

Windows 10, x64
Rust 1.40.0
Wasmtime 0.20.0

Additional information

• If I cargo build ... --release and use wasmtime to run the release build, it works.
• If I run the debug build on Linux (WSL Ubuntu), it works.

Wasmtime GitHub notifications bot (Oct 16 2020 at 11:18):

tschneidereit assigned Issue #2294 (assigned to yurydelendik):

When I write a program in Rust and compile it to WASM, I cannot run it under wasmtime on Windows unless I passed the --release flag when I built it. If I built the WASM module in debug mode, wasmtime gives the error "command export '__rustc_debug_gdb_scripts_section__' is not a function". All other combinations of OS and build mode work: the error is specific to debug builds under Windows.

Steps to reproduce

1. Get hold of a Windows box. Install Rust, the wasm32-wasi target and wasmtime.
2. cargo new a hello-world program.
3. cd into the hello-world directory and cargo build --target wasm32-wasi
4. Run wasmtime run .\target\wasm32-wasi\debug\hello-world.wasm

Results

Expected: Should print Hello, world!

Actual:

Error: failed to run main module `.\target\wasm32-wasi\debug\hello-world.wasm`

Caused by:
    0: failed to instantiate ".\\target\\wasm32-wasi\\debug\\hello-world.wasm"
    1: command export '__rustc_debug_gdb_scripts_section__' is not a function

Environment

Windows 10, x64
Rust 1.40.0
Wasmtime 0.20.0

Additional information

• If I cargo build ... --release and use wasmtime to run the release build, it works.
• If I run the debug build on Linux (WSL Ubuntu), it works.

Wasmtime GitHub notifications bot (Oct 16 2020 at 11:18):

tschneidereit commented on Issue #2294:

Sounds like an issue with debug info handling. @yurydelendik, can you take a look?

Wasmtime GitHub notifications bot (Oct 16 2020 at 11:32):

bjorn3 commented on Issue #2294:

__rustc_debug_gdb_scripts_section__ is exported by rustc to prevent LLVM from gcing a section that gdb reads to load the pretty printing python script for rust. That section normally contains the string gdb_load_rust_pretty_printers.py.

https://github.com/rust-lang/rust/blob/95b4a4f0eee935f9e0c80b0ceef34866bcb72ca3/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs#L37

Either Wasmtime should simply ignore this export instead of attempting to interpret it as command or rustc should stop adding this section for wasm.

Wasmtime GitHub notifications bot (Oct 16 2020 at 11:36):

tschneidereit commented on Issue #2294:

Thank you for the investigation, @bjorn3!

Either Wasmtime should simply ignore this export instead of attempting to interpret it as command or rustc should stop adding this section for wasm.

I think the former is preferable: we shouldn't rely on the compiler doing the right thing (assuming not adding this section would be the right thing, which I don't have enough context to know) about something like this.

Wasmtime GitHub notifications bot (Oct 21 2020 at 16:04):

yurydelendik commented on Issue #2294:

Looks unrelated to wasmtime debugging capabilities. Will the following help?

diff --git a/crates/wasmtime/src/linker.rs b/crates/wasmtime/src/linker.rs
index c22b89bf4..2f944050f 100644
--- a/crates/wasmtime/src/linker.rs
+++ b/crates/wasmtime/src/linker.rs
@@ -442,2 +442,5 @@ impl Linker {
                 warn!("command module exporting '__data_end' is deprecated");
+            } else if export.name() == "__rustc_debug_gdb_scripts_section__" && export.ty().global().is_some() {
+                // Allow an exported "__rustc_debug_gdb_scripts_section__" for compatibility with toolchains.
+                // See rustc logic for ".debug_gdb_scripts" section.
             } else if export.name() == "__heap_base" && export.ty().global().is_some() {

Wasmtime GitHub notifications bot (Oct 21 2020 at 16:05):

yurydelendik unassigned Issue #2294:

When I write a program in Rust and compile it to WASM, I cannot run it under wasmtime on Windows unless I passed the --release flag when I built it. If I built the WASM module in debug mode, wasmtime gives the error "command export '__rustc_debug_gdb_scripts_section__' is not a function". All other combinations of OS and build mode work: the error is specific to debug builds under Windows.

Steps to reproduce

1. Get hold of a Windows box. Install Rust, the wasm32-wasi target and wasmtime.
2. cargo new a hello-world program.
3. cd into the hello-world directory and cargo build --target wasm32-wasi
4. Run wasmtime run .\target\wasm32-wasi\debug\hello-world.wasm

Results

Expected: Should print Hello, world!

Actual:

Error: failed to run main module `.\target\wasm32-wasi\debug\hello-world.wasm`

Caused by:
    0: failed to instantiate ".\\target\\wasm32-wasi\\debug\\hello-world.wasm"
    1: command export '__rustc_debug_gdb_scripts_section__' is not a function

Environment

Windows 10, x64
Rust 1.40.0
Wasmtime 0.20.0

Additional information

• If I cargo build ... --release and use wasmtime to run the release build, it works.
• If I run the debug build on Linux (WSL Ubuntu), it works.

Wasmtime GitHub notifications bot (Oct 25 2020 at 13:47):

workingjubilee commented on Issue #2294:

If gdb can debug wasm, then rustc should continue adding the section for wasm targets.
If gdb cannot debug wasm, then rustc should not add the section.
I don't know gdb's limits here.

Wasmtime GitHub notifications bot (Oct 25 2020 at 13:48):

workingjubilee edited a comment on Issue #2294:

If gdb (and specifically the rust-gdb pretty printer) can debug wasm, then rustc should continue adding the section for wasm targets. If gdb cannot debug wasm, then rustc should not add the section.
I don't know rust-gdb's limits here.

Wasmtime GitHub notifications bot (Oct 26 2020 at 00:48):

workingjubilee edited a comment on Issue #2294:

If gdb (and specifically the rust-gdb pretty printer) can debug wasm, then rustc should (probably) continue adding the section for wasm targets. If gdb cannot debug wasm, then rustc should not add the section.
I don't know rust-gdb's limits here.

Last updated: Dec 23 2024 at 12:05 UTC