UPDATE-KERNEL(8)

💅 update-kernel(8) — bestie edition 🎀

ok so this is from the System Manager's Manual and it's called update-kernel, and literally the whole personality of this page is kernel glow-ups ✨ (plus modules and firmware, obvi).

---

🌸 NAME 🌸

update-kernel — update kernel, modules and firmware. that's it. that's the vibe check. 🫶

---

✨ SYNOPSIS ✨

update-kernel [-a ARCH] [-b BUILDDIR] [-c CACHEDIR] [-C COMPRESSION] [-d
KEYSDIR] [-e FIRMWARE] [-f FLAVOR] [-F FEATURE] [-h] [-k PUBKEY] [-K]
[-M] [-p PACKAGE] [-s] [-v] [DESTDIR]

---

💖 DESCRIPTION 💖

So update-kernel installs or updates the kernel, the kernel modules, and the firmware in a destination directory for an Alpine installation. no cap. it's got two whole modes and it ate: you can download pre-built kernels by flavor, or install custom-built kernels straight from a build directory. both iconic. 👑

Here's the literal lore of what the script does, step by step:

• it creates a modloop squashfs image containing modules and firmware,
• it builds an initramfs,
• and then it copies the kernel image, System.map, and config over to the destination.

On systems where the modloop is mounted, the destination is auto-detected from the modloop mount. and if you run it with zero arguments? it just updates the current running kernel. main character behaviour, honestly. 🧚

---

🔥 OPTIONS 🔥

• -a, --arch ARCH — target architecture (e.g. x86_64, aarch64). pick your fighter. 💪
• -b, --build-dir DIR — install a custom-built kernel from DIR. heads up bestie: mutually exclusive with -f. 🚫
• -c, --cache-dir DIR — override the apk cache directory. default: /etc/apk/cache.
• -C, --compression — initramfs compression method (see mkinitfs). squeeze it, babes. 🗜️
• -d, --keys-dir DIR — override the trusted apk keys directory.
• -e, --modloopfw FIRMWARE — install extra firmware file in the modloop, in addition to firmware detected by modinfo. the more the merrier fr fr.
• -f, --flavor FLAVOR — install kernel of specified flavor (e.g. virt, lts). mutually exclusive with -b, no exceptions. 💅
• -F, --feature FEATURE — enable an initfs feature. defaults to features from /etc/mkinitfs/mkinitfs.conf.
• -h, --help — display usage information and exit. the classic.
• -k, --apk-pubkey FILE — include the given apk public key in the initramfs. 🔑
• -K, --hostkeys — include host keys in the initramfs.
• -M, --media — boot media directory layout.
• -p, --package PACKAGE — additional module or firmware package to install. treat yourself. 🍓
• -s, --modloopsign — sign the modloop with the abuild signing key. signature moment. ✍️
• -v, --verbose — verbose output. she talks a LOT and we love that.
• --repositories-file FILE — override the apk repositories file. default: /etc/apk/repositories.

---

🌈 ENVIRONMENT 🌈

• TMPDIR — point to a storage-backed directory on low-memory systems. yes this is a real tip and not me guessing, it's literally what the page says. 🫡

---

⭐ EXIT STATUS ⭐

• 0 — success. we slayed. 🎉
• non-zero — an error occurred. 💀 it happens.

---

🦋 SEE ALSO 🦋

mkinitfs(8), mksquashfs(1), apk(8), setup-bootable(8), setup-alpine(8)

go read those next, iykyk 📚

---

👑 AUTHORS 👑

Timo Teras, Kaarle Ritvanen, Natanael Copa, and others. legends only. 💜

---

✨ mwah ✨ that's the whole page bestie — brought to you by Alpine Linux, dated 2026-06-09, and this rewrite of UPDATE-KERNEL(8) was a whole moment. go update that kernel, queen. 🌸💅🎀