Stream: git-wasmtime

Topic: wasmtime / issue #10244 Conditionally remove page-alignme...

Wasmtime GitHub notifications bot (Feb 19 2025 at 20:30):

alexcrichton opened issue #10244:

Currently Wasmtime will allocate space in *.cwasm files to ensure that sections are page-aligned on disk. This is done for two reasons:

• When mmap-ing a *.cwasm into the address space the .text section needs to be made executable and we don't want to make non-code executable, meaning that the start/end of the .text section are both page aligned. The base alignment is set here and the alignment for the end is set here.
• When memory_init_cow is enabled then it's necessary to mmap the .rodata section from the *.cwasm into the address space, meaning the start of the data section is also aligned. The data section alignment is set here. The data_align value is set here

When writing up this issue I thought we'd need to fix both these locations but it turns out we already conditionally set data_align by skipping that method if memory_init_cow isn't called. That means that I think the only thing we need to do here is to update compilation to Pulley to use a different alignment for the text section. We already have some logic for conditionally making the .text section executable, so we mostly just need to propagate similar logic back to the actual creation of the *.cwasm file.

Wasmtime GitHub notifications bot (Feb 27 2025 at 18:01):

alexcrichton added the enhancement label to Issue #10244.

Wasmtime GitHub notifications bot (Feb 27 2025 at 18:01):

alexcrichton added the wasmtime label to Issue #10244.

Wasmtime GitHub notifications bot (Feb 27 2025 at 18:01):

alexcrichton added the wasmtime:code-size label to Issue #10244.

Last updated: Feb 28 2025 at 02:27 UTC