# Reproducible Builds September 2026 report: dettrace updates and summit news

> **Key takeaway:** The Reproducible Builds project reported significant progress in tool support for PGO and Lisp dumps, alongside updates to the SOURCE_DATE_EPOCH specification.

**Published:** 2026-10-14T18:34:14+00:00 
**Source:** Planet Debian (Developer Blogs) 
**Category:** distro-planet 
**Canonical URL:** https://fosswire.org/news/reproducible-builds-september-2026-report-dettrace-updates-a.html 

## Summary
The September 2026 report from the Reproducible Builds project highlights the recent summit in Gothenburg and major updates to the dettrace tool. dettrace now supports most architectures used by Debian and openSUSE, enabling deterministic builds for Profile-Guided Optimisations (PGO) and various Lisp/Scheme memory dumps. Additionally, the project is reviewing proposed changes to the SOURCE_DATE_EPOCH specification.

## Technical developments in dettrace and specifications
- **dettrace** has been ported to most architectures supported by Debian and openSUSE, improving stability for production pipelines.
- The tool now enables deterministic builds when using **Profile-Guided Optimisations (PGO)**, preventing performance loss during reproducibility efforts.
- Support has been added for **Lisp and Scheme memory dumps**, including CLISP, SBCL, Scheme 48, Racket, and GNU Emacs.
- Seven independent proposals have been submitted via Salsa to update the **SOURCE_DATE_EPOCH** specification.

## Why it matters
These updates reduce the trade-off between software performance and build integrity, particularly for complex language environments and optimized binaries.