Agent-Skills.md

Agent Skills: AlmaLinux 10+ Knowledge Patch

AlmaLinux changes since training cutoff (latest: 10.1) — Btrfs root support, x86-64-v2 builds, post-quantum crypto via OpenSSL 3.5, SPICE re-enabled, CRB repo on by default. Load before working with AlmaLinux.

UncategorizedID: nevaberry/nevaberry-plugins/almalinux-knowledge-patch

Repository

nevaberry/nevaberry-plugins
NevaberryLicense: MIT
15

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pnpm dlx add-skill https://github.com/Nevaberry/nevaberry-plugins/tree/HEAD/plugins/almalinux-knowledge-patch/skills/almalinux-knowledge-patch

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plugins/almalinux-knowledge-patch/skills/almalinux-knowledge-patch/SKILL.md

Skill Metadata

Name
almalinux-knowledge-patch
Description
"AlmaLinux changes since training cutoff (latest: 10.1) — Btrfs root support, x86-64-v2 builds, post-quantum crypto via OpenSSL 3.5, SPICE re-enabled, CRB repo on by default. Load before working with AlmaLinux."

AlmaLinux 10+ Knowledge Patch

Claude's baseline knowledge covers AlmaLinux through 9.3. This skill provides changes from 10.1 (2025-11-24) onwards.

AlmaLinux 10 is based on RHEL 10 (kernel 6.12) but includes several significant deviations that differentiate it from upstream RHEL and other RHEL rebuilds.

Quick Reference

Breaking Changes / Key Differences from RHEL 10

| Feature | RHEL 10 | AlmaLinux 10 | |---------|---------|--------------| | Btrfs | Not supported | Full kernel + userspace; can install/boot from Btrfs | | CPU baseline | x86-64-v3 only | x86-64-v2 AND x86-64-v3 builds | | CRB repo | Disabled by default | Enabled by default on new installs | | SPICE | Removed | Re-enabled (server + client) | | Frame pointers | Not default | Enabled by default (system-wide profiling) | | KVM on POWER | Removed | Re-enabled | | Firefox/Thunderbird | Flatpak-only | Regular RPMs |

Btrfs Support

AlmaLinux 10 is the only RHEL-based distro with full Btrfs support. You can use Btrfs as root filesystem during installation.

# Btrfs is available in the default kernel — no extra packages needed
mkfs.btrfs /dev/sda1
mount -o compress=zstd,noatime /dev/sda1 /mnt

# Subvolume management works out of the box
btrfs subvolume create /mnt/@home
btrfs subvolume snapshot -r /mnt/@home /mnt/@home-snapshot

# Check filesystem usage
btrfs filesystem usage /mnt

x86-64-v2 Architecture Support

RHEL 10 raised the CPU baseline to x86-64-v3 (requires AVX2 — Intel Haswell+ / AMD Excavator+). AlmaLinux ships additional x86-64-v2 builds for older CPUs.

Important caveat: Third-party packages built for RHEL 10 target x86-64-v3 only. The v2 support is limited to AlmaLinux's own repository packages — third-party RHEL 10 packages may fail with SIGILL on v2 hardware.

# Check CPU architecture level support
/lib64/ld-linux-x86-64.so.2 --help 2>&1 | grep supported

CRB Repository

On new AlmaLinux 10 installations, CRB (CodeReady Builder) is enabled by default — development headers and build dependencies are available without manual repo activation.

# Previously required on RHEL/AlmaLinux 9:
#   dnf config-manager --set-enabled crb

# On AlmaLinux 10+ new installs, already enabled
dnf repolist | grep crb

# Note: upgrades from AlmaLinux 9 preserve existing repo configuration

Frame Pointers Enabled by Default

All packages are compiled with frame pointers, enabling system-wide profiling without recompilation:

# System-wide profiling works out of the box
perf record -g -a -- sleep 10
perf report

SPICE, KVM on POWER, Firefox/Thunderbird

  • SPICE: Re-enabled for server and client (removed in RHEL 10)
  • KVM on IBM POWER: Re-enabled in virtualization stack (removed in RHEL 10)
  • Firefox/Thunderbird: Shipped as regular RPMs, not Flatpak-only as in RHEL 10
# Regular RPM install (not Flatpak)
dnf install firefox thunderbird

Post-Quantum Cryptography

System-wide crypto policies enable PQC algorithms by default in AlmaLinux 10:

  • OpenSSL 3.5: Adds ML-KEM (Kyber), ML-DSA (Dilithium), SLH-DSA (SPHINCS+)
  • TLS: Hybrid ML-KEM is in the default TLS group list — connections auto-negotiate PQC when both sides support it
  • RPM signatures: RPMv6 supports PQC via Sequoia PGP tools

No configuration needed — PQC is active out of the box with default crypto policies.

See references/pqc-and-crypto.md for algorithm details.

Key Toolchain Versions (AlmaLinux 10.1)

| Tool | Version | Notes | |------|---------|-------| | GCC | 14.3.1 | Default compiler | | GCC Toolset 15 | GCC 15.1 | dnf install gcc-toolset-15 | | Go | 1.24 | | | LLVM/Clang | 20.1 | | | Rust | 1.88 | | | Python | 3.12.11 | Default system Python | | Node.js | 24 | | | Podman | 5.6 | | | QEMU-KVM | 10.0 | | | Kernel | 6.12 | Frame pointers enabled |

See references/toolchain-versions.md for details.

Dockerfile Base Image

FROM almalinux:10
# or for minimal: FROM almalinux:10-minimal (uses microdnf)

Reference Files

| File | Contents | |------|----------| | almalinux-deviations.md | Full details on AlmaLinux vs RHEL 10 differences | | pqc-and-crypto.md | Post-quantum cryptography algorithms and configuration | | toolchain-versions.md | Compiler, runtime, and tool versions in 10.1 |