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FS#63238 - [systemd] 242.32-3 incompatible with Zen+ (**NOT** Zen/Zen2) Ryzen CPUs, unbootable

Attached to Project: Arch Linux
Opened by Noëlle Mercer (noellemercer) - Saturday, 20 July 2019, 18:09 GMT
Task Type Bug Report
Category Packages: Core
Status Unconfirmed
Assigned To No-one
Architecture x86_64
Severity Critical
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 1
Private No


Description: With my system, a Dell Inspiron 15 5585, Arch is not installable or bootable; attempting to boot simply gives a black screen with no information. This is likely to be a systemd bug, as there have been reports of successful boots when using OpenRC/sysvinit instead of systemd when I asked about this issue on Reddit. My computer's specs are as follows:

* CPU and GPU: AMD Ryzen 7 3700U Mobile Processor with Radeon Vega 10 (a "Zen+" CPU, a weird "middling" architecture, different from Zen and Zen2)
* RAM: 16GB DDR4-2400
* SSD: 512GB M.2 PCIe
* WLAN: Qualcomm QCA9377

Things I have tried:

* Booting with the official release Arch ISO from 2019-07-01: Same issue occurs, a black screen on boot.
* Booting with an Arch ISO created with archiso, including the latest packages/systemd: Same issue occurs, a black screen on boot.
* Booting with SecureBoot on and off: Same issue occurs both ways, a black screen on boot.
* Booting with nomodeset and variants: Same issue occurs, a black screen on boot.
* Booting in legacy/BIOS mode: A kernel panic occurs. Text printed on screen is cutoff and illegible.

Additional info:
* [systemd] 242.32-3
* No log files; nothing is printed to the screen, it remains black. In legacy mode, text is illegible.
* No upstream bug report, open or closed.

Steps to reproduce:

1. Have a CPU
2. Build an Arch ISO with archiso including the latest systemd (the release installer has an old version that is also broken on Zen2)
3. Attempt to boot, observe a black screen regardless of kernel parameters, settings, etc.
This task depends upon

2019-07-20: A task closure has been requested. Reason for request:
Comment by Noëlle Mercer (noellemercer) - Saturday, 20 July 2019, 18:18 GMT

Steps to reproduce:
1. Have a **Zen+** CPU
Comment by loqs (loqs) - Saturday, 20 July 2019, 18:32 GMT
Can you please try the 2018.12.01 installation media to test if it is related RDRAND
Alternately can you boot a busbybox based initrd (one generated by mkinitcpio without the systemd hook) with the option break which should leave the system at a rescue shell.
Comment by AK (Andreaskem) - Saturday, 20 July 2019, 19:17 GMT