How the Linux User/Kernel ABI Really Works - Greg Law - C++Now 2025

https://www.cppnow.org​
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How the Linux User/Kernel ABI Really Works - Driving the Linux Kernel Down at the Metal - Greg Law - C++Now 2025
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All programs need to interact with the wider system in order to do useful work. C and C++ programmers typically write to the C library as the lowest layer: an abstraction onto the OS that is a not-quite-perfect model.

It is often useful to understand the ABI you are really programming to, e.g. when you're debugging without source code available, doing fine-grained profiling and optimisation, writing intercept libraries, etc.

This talk covers how system calls are really implemented (int 0x80, syscall, the vdso and the vsyscall page, and how return codes are translated into errno); how signal handlers really work (including the surprising syscall restart mechanism); how pthreads map onto OS primitives; the finer details of ptrace (the mechanism on top of which strace and gdb are built); and some interesting and surprising results when the subtleties of these various mechanism combine. Other subtleties covered include how the kernel deals with different kinds of signal, scheduling states such as 'uninterruptible sleep', and some of the very useful info that can be gathered from the /proc pseudo filesystem.
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Slides: https://github.com/boostcon/cppnow_pr...

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Greg Law

Greg is the co-founder and CEO of Undo.io. He is a coder at heart, but likes to bridge the gap between the business and software worlds.

Greg's experience includes creating and working on Operating Systems, Networking Stacks and Developer Tools. He has held development and management roles at companies including the pioneering British computer firm Acorn, as well as fast-growing start ups, NexWave and Solarflare. It was at Acorn that Greg met Julian and on evenings and weekends, they invented the core technology that would eventually become Undo.

Greg holds a PhD from City University, London and was nominated for the 2001 British Computer Society Distinguished Dissertation Award. He lives in Cambridge, UK with his wife and two children and in his spare time, catches up on email.


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C++Now 2026 - 27th April - 1st May
C++Now is an annual onsite international C++ programming and coding conference held in Aspen, Colarado. For all C++ developers, C++ software engineers and those involved with the C++ language, CppNow provides an indepth and technical content provided by the best and brightest C++ experts of the C++ world.
Annual CppNow Conference - https://www.cppnow.org
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