Thread (12 messages) 12 messages, 5 authors, 2021-01-18

Re: Multiple MODALIAS= in uevent file confuses userspace

From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: 2021-01-18 13:54:15
Also in: lkml

CC Mika and Andy.

On Mon, Jan 18, 2021 at 8:27 AM Kai-Heng Feng
[off-list ref] wrote:
On Sat, Jan 9, 2021 at 12:25 AM Kai-Heng Feng
[off-list ref] wrote:
quoted
Commit 8765c5ba19490 ("ACPI / scan: Rework modalias creation when
"compatible" is present") creates two modaliases for certain ACPI
devices. However userspace (systemd-udevd in this case) assumes uevent
file doesn't have duplicated keys, so two "MODALIAS=" breaks the
assumption.

Based on the assumption, systemd-udevd internally uses hashmap to
store each line of uevent file, so the second modalias always replaces
the first modalias.

My attempt [1] is to add a new key, "MODALIAS1" for the second
modalias. This brings up the question of whether each key in uevent
file is unique. If it's no unique, this may break may userspace.
Does anyone know if there's any user of the second modalias?
If there's no user of the second one, can we change it to OF_MODALIAS
or COMPAT_MODALIAS?

Kai-Heng
quoted
[1] https://github.com/systemd/systemd/pull/18163

Kai-Heng
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