Dear Linux folks,
This is an interesting one. On a Dell Precision 3540 with a dedicated
AMD graphics card, and with Debian Sid/unstable and Linux 5.6.14, there
are several strange issues (one example [1]).
Starting the system, and adding `maxcpus=1` to the Linux command line,
the system starts.
Trying to bring up more CPUs, works for the first one, but fails for the
second. The system freezes then. Nothing is dumped on the Linux virtual
terminal.
In my limited tests, this always happens, when the system runs on
batteries, that means, without the power cord plugged in. But I was also
able to reproduce it with the USB Type-C power cable plugged in. But
sometimes it works (to bring all other seven CPUs online).
Please find the Linux messages up to bringing CPU 1 online attached with
no power cord plugged in, and the messages of a successful operation.
Is this expected? I’d appreciated tips, if it’s possible to debug this
further.
Kind regards,
Paul
[1]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1883065
> -----Original Message-----
> From: Paul Menzel <[email protected]>
> Sent: Thursday, June 11, 2020 3:59 AM
> To: Thomas Gleixner; Ingo Molnar; Borislav Petkov
> Cc: [email protected]; LKML; Limonciello, Mario; Hans de Goede; Christian
> Kellner; [email protected]
> Subject: Intel laptop: Starting with `maxcpus=1` and then bringing other
> CPUs online freezes system
>
>
> [EXTERNAL EMAIL]
>
> Dear Linux folks,
>
>
> This is an interesting one. On a Dell Precision 3540 with a dedicated
> AMD graphics card, and with Debian Sid/unstable and Linux 5.6.14, there
> are several strange issues (one example [1]).
>
> Starting the system, and adding `maxcpus=1` to the Linux command line,
> the system starts.
>
> Trying to bring up more CPUs, works for the first one, but fails for the
> second. The system freezes then. Nothing is dumped on the Linux virtual
> terminal.
>
> In my limited tests, this always happens, when the system runs on
> batteries, that means, without the power cord plugged in. But I was also
> able to reproduce it with the USB Type-C power cable plugged in. But
> sometimes it works (to bring all other seven CPUs online).
>
> Please find the Linux messages up to bringing CPU 1 online attached with
> no power cord plugged in, and the messages of a successful operation.
>
> Is this expected? I’d appreciated tips, if it’s possible to debug this
> further.
>
>
> Kind regards,
>
> Paul
>
>
> [1]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1883065
From some other similar reports I've heard this could be related to the ucode
loading causing a freeze. I would suggest trying to disable the Intel ucode
loader with the initramfs as a debugging tactic.
On Thu, Jun 11, 2020 at 01:13:27PM +0000, [email protected] wrote:
> From some other similar reports I've heard this could be related to the ucode
> loading causing a freeze. I would suggest trying to disable the Intel ucode
> loader with the initramfs as a debugging tactic.
There's a cmdline param for that: "dis_ucode_ldr".
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette