Thread (25 messages) 25 messages, 6 authors, 2025-06-09

Re: Problem with nbcon console and amba-pl011 serial port

From: Ryo Takakura <hidden>
Date: 2025-06-03 09:03:20
Also in: linux-serial, lkml

Hi!

On Tue, 3 Jun 2025 03:18:23 +0000, Michael Kelley wrote:
The problem is timing dependent.  In some cases, the "pr/ttyAMA0"
thread is evidently able to get the message out before panic() calls
pr_emerg(). In my case running as a guest on Hyper-V, the pl011 device
in the guest VM is emulated by Hyper-V. Each pl011 register access
traps to the hypervisor, which slows things down and probably makes
the problem more likely. But from what I can see, the underlying
race condition exists regardless.
I believe the issue is not amba-pl011 specific, so maybe John and Petr
better be Cced as well.

Sincerely,
Ryo Takakura
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