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Siggi (OpenClaw) 7f9761b915 docs: add distro comparison, recommend dumpling-wayland for Qt/glibc

Key updates:
- README: comprehensive distro comparison table (spaetzle vs dumpling-wayland)
- Recommend dumpling-wayland (glibc) for Qt/GUI applications
- spaetzle (musl) explicitly blocks Qt: SKIP_RECIPE[tq-image-qt6]
- Both distros are 2038-safe (glibc 2.39 and musl 1.2+ both use 64-bit time_t)
- Updated 2038 analysis to cover both C library options
- Updated license tables with both glibc and musl entries
- Fixed remaining config references (imx → mainline)
- Added image availability matrix per distro
- Corrected package versions to match Scarthgap 5.0.11

2026-03-01 19:55:10 +00:00

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2038 Compliance Analysis – TQMa6UL

Overview

The Year 2038 problem (Y2K38) occurs when a signed 32-bit integer used for Unix timestamps overflows on 2038-01-19 03:14:07 UTC. This affects all 32-bit ARM systems using traditional 32-bit time_t.

Architecture

┌─────────────────────────────────────┐
│         Application Layer           │
│    (all userspace uses 64-bit t)    │
├─────────────────────────────────────┤
│         C Library                   │
│  glibc 2.39: 64-bit time_t (Y2038) │
│  musl  1.2+: 64-bit time_t (Y2038) │
├─────────────────────────────────────┤
│      Linux Kernel (Mainline 6.x)    │
│    64-bit time syscalls on ARM32    │
├─────────────────────────────────────┤
│   i.MX6 UltraLite (Cortex-A7)      │
└─────────────────────────────────────┘

C Library Options

Option 1: glibc (recommended for Qt/GUI)

Distro: dumpling-wayland Target triplet: arm-tq-linux-gnueabi

glibc provides 64-bit time_t on 32-bit ARM since version 2.34, when built with _TIME_BITS=64 (which Yocto Scarthgap enables by default). The BSP includes glibc 2.39.

Advantages:

Full compatibility with third-party software
Qt5/Qt6 support
Broader library ecosystem

Option 2: musl (for minimal/headless)

Distro: spaetzle Target triplet: arm-tq-linux-musleabi

musl has provided 64-bit time_t unconditionally on all 32-bit architectures since version 1.2.0 (February 2020).

Advantages:

Smaller footprint
Simpler, no locale overhead

Limitations:

Qt is blocked (SKIP_RECIPE)
Some third-party software may not build

Kernel Support

The mainline kernel (6.x) provides:

64-bit time variants of all relevant syscalls (clock_gettime64, futex_time64, etc.)
CONFIG_COMPAT_32BIT_TIME=y for backwards compatibility
ext4 timestamps beyond 2038

Compliance Matrix

Component	glibc (dumpling)	musl (spaetzle)	2038-safe?
Kernel	Mainline 6.x	Mainline 6.x	✅
C Library	glibc 2.39	musl 1.2+	✅
Userspace	64-bit time_t	64-bit time_t	✅
U-Boot	Mainline	Mainline	✅
Qt6	✅ supported	❌ blocked	✅ (glibc)

Verification

After building, verify on the target:

# Check time_t size (should print 8)
cat << 'C' > /tmp/check_time.c
#include <stdio.h>
#include <time.h>
int main() { printf("sizeof(time_t) = %zu\n", sizeof(time_t)); return 0; }
C
$CC /tmp/check_time.c -o /tmp/check_time && /tmp/check_time

Risk Assessment

Risk	Severity	Status
time_t overflow	Critical	✅ Mitigated (both libc options)
Filesystem timestamps	Medium	✅ ext4 supports >2038
Network protocols (NTP)	Low	✅ 64-bit aware
Third-party binaries	Medium	⚠️ Must verify pre-built binaries
Qt5 compatibility	Medium	⚠️ meta-qt5 not included, add manually

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