IBV_IS_F...ITIALIZED(3)

💅 IBV_IS_F...ITIALIZED(3) 💅

okay so bestie, we're deep in the Libibverbs Programmer's Manual today and this one is a little sleeper hit ngl — it's giving "short page, important vibe check." Let's get into it 🫶

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✨ NAME ✨

ibv_is_fork_initialized — the lil function that tells you whether fork support (aka ibv_fork_init) is enabled or not. literally just a status check, no drama 💖

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🌸 SYNOPSIS 🌸

#include <infiniband/verbs.h>

enum ibv_fork_status {
    IBV_FORK_DISABLED,
    IBV_FORK_ENABLED,
    IBV_FORK_UNNEEDED,
};

enum ibv_fork_status ibv_is_fork_initialized(void);

look at that enum, she's iconic 👑

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🦋 DESCRIPTION 🦋

so ibv_is_fork_initialized() is basically the receipts-checker: it looks at whether libibverbs fork() support was turned on through the ibv_fork_init() verb. that's it. that's the whole job. lowkey obsessed with how straightforward she is 💅

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🎀 RETURN VALUE 🎀

here's the tea, three possible answers:

• returns IBV_FORK_DISABLED if fork support is disabled 🙈
• returns IBV_FORK_ENABLED if it's enabled ✨
• returns IBV_FORK_UNNEEDED, which is the fun one — it means the kernel copies DMA pages on fork, so calling ibv_fork_init() is literally unneeded. no cap, you can just chill 😌

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⭐ NOTES ⭐

okay important plot twist: the IBV_FORK_UNNEEDED return value takes precedence over both IBV_FORK_DISABLED and IBV_FORK_ENABLED. so if the kernel supports copy-on-fork for DMA pages, IBV_FORK_UNNEEDED gets returned regardless of whether ibv_fork_init() was called or not. fr fr, doesn't matter what you did, the kernel said what it said 💀

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🌈 SEE ALSO 🌈

• fork(2)
• ibv_fork_init(3)

go read those too bestie, iykyk 📚

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💜 AUTHOR 💜

big shoutout to Gal Pressman <galpress@amazon.com> for bringing us this one 🫶

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and that's the whole page!! this gem is from libibverbs, dated 2020-10-09 — a certified classic from the Libibverbs Programmer's Manual era 🧚✨ slay, bye!! 💖