microsoft / microsoft/litebox

Linux kernel CPU mask vs Hyper-V VP index

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#677 2 comments 0 reactions 0 assignees View on GitHub

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target-lvbs
Dominant language
Rust
Stars
2.7k
Forks
144
Avg merge
12h 21m
Merged PRs (30d)
146

Description

Both Linux kernel and Hyper-V have their own logical CPU identifiers. Their index values are often the same, but this is not architecturally guaranteed (e.g., NUMA topology). To this end, Linux kernel maintains the hv_vp_index array to map Linux CPU IDs to Hyper-V VP indexes. The LVBS platform needs this array to reliably map Linux CPU IDs (e.g.,cpu_online_mask) to VP indexes to selectively initialize VTL1.

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First steps

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Research direction

Start by tracing LVBS platform initialization and how it can access the Linux kernel's hv_vp_index mapping, using cpu_online_mask and VTL1 initialization as the relevant entry points. Done means Linux CPU IDs are reliably mapped to Hyper-V VP indexes so VTL1 can be initialized selectively, including when NUMA topology makes the indexes differ.

Written by the indexing model from the issue text.

Assessment

Tech stack
linux, rust
Domain
operating-systems
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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