RPi5 dom0less: instability when preloading Android trout DomU alongside Zephyr + Linux DomD

[Aananth C N <c.n.aananth@xxxxxxxxx>]

Dear Xen-Troops Team,

I am working on a Xen dom0less setup on Raspberry Pi 5 (ARM64) with the following intended layout:

• Xen hypervisor

• Zephyr as Dom0

• Linux (Yocto-based) as DomD

• Android (trout image) as an additional DomU

My goal is to preload the Android kernel + ramdisk as multiboot modules via U-Boot and have Xen instantiate it as a secondary DomU alongside the existing dom0less guests.

However, I am observing fragile and non-deterministic behaviour, mainly affecting Linux DomD stability. Depending on the RAM addresses used for preloading Android images, I see:

• DomD failing to boot or console becoming non-responsive

• Xen warnings (vGIC / SMC-HVC related)

• In some cases, U-Boot synchronous abort before Xen hand-off

Example preload address ranges tested:

• 0x18000000 / 0x1A800000 / 0x1B000000 → DomD unstable / fails

• ~0x68000000 → occasionally works but not reliable

• ~0x70000000 → U-Boot abort observed

Xen logs show DomD static banks such as:

• 0x50000000 – 0x68000000

• 0x20000000 – 0x28000000

Even when placing Android images outside these ranges, DomD behaviour becomes unstable.

Could you advise on:

1. Recommended approach for hosting a full Android kernel guest alongside Zephyr + Linux dom0less guests on ARM / RPi5

2. Safe multiboot module placement expectations for dom0less

3. Any known limitations related to BCM2712 / RP1 memory topology

I can share full logs, DT snippets, and boot scripts if helpful.

Best regards,
Aananth