Re: Linux 6.5 speed regression, boot VERY slow with anything systemd related

From: Marc Haber
Date: Wed Sep 06 2023 - 16:19:09 EST


On Wed, Sep 06, 2023 at 06:26:16PM +0300, Tony Lindgren wrote:
> * Marc Haber <mh+linux-kernel@xxxxxxxxxxxx> [230906 14:41]:
> > With my tools I have found out that it really seems to be related to the
> > CPU of the host. I have changed my VM definition to "copy host CPU
> > configuration to VM" in libvirt and have moved this very VM (image and
> > settings) to hosts with a "Ryzen 5 Pro 4650G" and to an "Intel Xeon
> > E3-1246" where they work flawlessly, while on both APUs I have available
> > ("AMD G-T40E" and "AMD GX-412TC SOC") the regression in 6.5 shows. And
> > if I boot other VMs on the APUs with 6.5 the issue comes up. It is a
> > clear regression since going back to 4.6's serial code solves the issue
> > on the APUs.
>
> Not sure why the CPU matters here..

Neither am I.

> One thing to check is if you have these in your .config:
>
> CONFIG_SERIAL_CORE=y
> CONFIG_SERIAL_CORE_CONSOLE=y

That's affirmative. Otherwise, I think that serial console wouldn't work
at all, but I get early kernel messages just fine and even at normal
speed.

> Or do you maybe have CONFIG_SERIAL_CORE=m as loadable module?

Negative.

Greetings
Marc

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