`syscall(SYS_pidfd_open)` should produce clear error when `ENOSYS`

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#549 opened on Feb 23, 2026 2 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 3/5
Estimated time: 1-2 days
Newbie friendliness: 45/100

Issue type: Bug
Clarity: Mostly clear
Activity status: Stale
Tech stack: cpp
Domain: operating-systems

Research direction

Start in config.hpp and trace the V2 process-spawn path that calls syscall(SYS_pidfd_open). Reproduce the older-kernel ENOSYS case and verify that it reports a clear exception instead of the misleading Bad file descriptor error.

Written by the indexing model from the issue text.

Description

While building on an older Linux kernel for compatibility, all V2 process spawns failed with Bad file descriptor. We traced this back to syscall(SYS_pidfd_open) returning -1 and errno == ENOSYS.

In config.hpp, even though SYS_pidfd_open is #defined, it doesn't appear to mean that it will work.

We now detect and define BOOST_PROCESS_V2_DISABLE_PIDFD_OPEN and things work as expected, but it took some time to figure out that we needed to do this.

It would be nice if an exception was thrown when this failed syscall produced ENOSYS.

Dominant language: C++
Stars: 145
Forks: 151
PR merge metrics: No merged PRs in 30d

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