SYSTEMD-....SERVICE(8)

💤 SYSTEMD-....SERVICE(8) 💤

okay bestie, this one is literally the hibernation wake-up call page from the systemd-hibernate-resume.service corner of the systemd manual. she's niche, she's powerful, she's giving "3am nap energy but make it kernel-level". let's get into it 🦋

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✨ NAME ✨

systemd-hibernate-resume.service, systemd-hibernate-clear.service, systemd-hibernate-resume — Resume from hibernation 💖

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🌸 SYNOPSIS 🌸

systemd-hibernate-resume.service

systemd-hibernate-clear.service

/usr/lib/systemd/systemd-hibernate-resume

like yes, three whole entries, no cap. one service, one other service, one binary. main character trio 👑

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💅 DESCRIPTION 💅

so systemd-hibernate-resume.service initiates the resume from hibernation. that's her whole job. that's the assignment and she ate it.

systemd-hibernate-resume only supports the in-kernel hibernation implementation, see Swap suspend[1] (footnote bestie, we'll get there). internally? the way that it works is by writing the major:minor of the selected device node to /sys/power/resume, along with the offset in memory pages (/sys/power/resume_offset) if that's supported. lowkey genius, highkey unhinged, we love her.

the resume device node is either passed directly through arguments, or automatically acquired from kernel command line options and/or the HibernateLocation EFI variable. the latter will normally be cleared by systemd-hibernate-resume.service on resumption, periodt. and if a stale variable gets detected? yeah, that one would be cleared by systemd-hibernate-clear.service. she's the cleanup crew 🧹✨

not me having to say this but — failing to initiate a resume is NOT an error condition. it may mean there was no resume image (e.g. if the system has been simply powered off and not hibernated). in such cases, the boot is ordinarily continued. so like, breathe, it's fine 💀

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🌈 SEE ALSO 🌈

• systemd(1)
• systemd-hibernate-resume-generator(8)

go read those too, iykyk 📚

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🎀 NOTES 🎀

1. Swap suspend https://docs.kernel.org/power/swsusp.html

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and that's the whole vibe check bestie — this page is from systemd 262.1, the systemd-hibernate-resume.service manual, brought to you by the systemd girlies. sleep well, resume better 💜🫶🦋