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Wasm is gaining popularity outside the Web as a well-specifed low-level binary format with ISA portability, low memory footprint and polyglot targetability, enabling efficient in- process sandboxing of untrusted code. Despite these advantages, Wasm adoption for new domains is often hindered by the lack of many standard system interfaces which precludes reusability of existing software and slows ecosystem growth. This paper proposes thin kernel interfaces for Wasm, which directly expose OS userspace syscalls without breaking intra- process sandboxing, enabling a new class of virtualization with Wasm as a universal binary format. By virtualizing the bottom layer of userspace, kernel interfaces enable effortless application ISA portability, compiler backend reusability, and armor programs with Wasm’s built-in control flow integrity and arbitrary code execution protection. Furthermore, existing capability-based APIs for Wasm, such as WASI, can be implemented as a Wasm module over kernel interfaces, improving reuse, robustness, and portability through better layering. We present an implementation of this concept for two kernels – Linux and Zephyr – by extending a modern Wasm engine and evaluate our system’s performance on a number of sophisticated applications which can run for the first time on Wasm. 

Heisenbugs, notorious for their ability to change behavior and elude reproducibility under observation, are among the toughest challenges in debugging programs. They often evade static detection tools, making them especially prevalent in cyber-physical edge systems characterized by complex dynamics and unpredictable interactions with physical environments. Although dynamic detection tools work much better, most still struggle to meet low enough jitter and overhead performance requirements, impeding their adoption. More importantly however, dynamic tools currently lack metrics to determine an observed bug's difficulty or heisen-ness undermining their ability to make any claims regarding their effectiveness against heisenbugs. This paper proposes a methodology for detecting and identifying heisenbugs with low overheads at scale, actualized through the lens of dynamic data-race detection. In particular, we establish the critical impact of execution diversity across both instrumentation density and hardware platforms for detecting heisenbugs; the benefits of which outweigh any reduction in efficiency from limited instrumentation or weaker devices. We develop an experimental WebAssembly-backed dynamic data-race detection framework, Beanstalk, which exploits this diversity to show superior bug detection capability compared to any homogeneous instrumentation strategy on a fixed compute budget. Beanstalk's approach also gains power with scale, making it suitable for low-overhead deployments across numerous compute nodes. Finally, based on a rigorous statistical treatment of bugs observed by Beanstalk, we propose a novel metric, the heisen factor, that similar detectors can utilize to categorize heisenbugs and measure effectiveness. We reflect on our analysis of Beanstalk to provide insight on effective debugging strategies for both in-house and in deployment settings. 

Abstract Wind-blown dust plays a critical role in numerous geophysical and biological systems, yet current models fail to explain the transport of coarse-mode particles (>5 μm) to great distances from their sources. For particles larger than a few microns, electrostatic effects have been invoked to account for longer-than-predicted atmospheric residence times. Although much effort has focused on elucidating the charging processes, comparatively little effort has been expended understanding the stability of charge on particles once electrified. Overall, electrostatic-driven transport requires that charge remain present on particles for days to weeks. Here, we present a set of experiments designed to explore the longevity of electrostatic charge on levitated airborne particles after a single charging event. Using an acoustic levitator, we measured the charge on particles of different material compositions suspended in atmospheric conditions for long periods of time. In dry environments, the total charge on particles decayed in over 1 week. The decay timescale decreased to days in humid environments. These results were independent of particle material and charge polarity. However, exposure to UV radiation could both increase and decrease the decay time depending on polarity. Our work suggests that the rate of charge decay on airborne particles is solely determined by ion capture from the air. Furthermore, using a one-dimensional sedimentation model, we predict that atmospheric dust of order 10 μm will experience the largest change in residence time due to electrostatic forces.