microsoft / microsoft/snmalloc

OpenBSD support

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OpenBSD platforms
Dominant language
C++
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Description

We currently have OpenBSD in CI, but the system is failing to initialise the pagemap.

I believe this is because the pagemap is very large, and OpenBSD does not support overcommit. I could not find a MAP_NORESERVE like flag that could be used.

Given the current design, I do not see a way to support an OS that does not separate the concept of reserve and commit, either explicitly as in Windows, or implicitly as in Linux and FreeBSD.

I am raising this issue to track thoughts on this.

@nwf-msr, @davidchisnall, @devnexen

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the current pagemap initialization path and the OpenBSD CI configuration referenced by the issue. Investigate how the allocator handles reserve and commit assumptions on supported systems, then determine what would constitute successful OpenBSD initialization and passing CI.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
operating-systems
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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