[systemd-devel] how to debug kernel panic which generated by udevadm at systemd?

[Mantas Mikulėnas]

On Tue, Oct 15, 2019 at 3:02 PM www <ouyangxuan10 at 163.com> wrote:

> Dear all,
>
> I add a new driver to kernel, and it probe success. When enter into
> systemd, the udevadm generate a kernel panic.
> I want to ask how to debug it and find out where the error occurred? When
> did udevadm load? What commands are used by udevadm, and what are the
> specific operations?
>

There aren't many udevadm calls in systemd... The main one is
systemd-udev-trigger.service, which calls `udevadm trigger
--type=subsystems --action=add`, then repeats the same for type=devices. It
tries to generate coldplug uevents by writing 'add' to each found device's
/sys/.../uevent file.

(The second is systemd-udev-settle.service, but it is disabled by default
on most systems and just waits for udev's job queue to empty.)

-- 
Mantas Mikulėnas
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