Public bug reported:
The Dell UART backlight driver creates a serial0-0 serdev device without ACPI
or Device Tree firmware metadata. When userspace reads its modalias sysfs
file, serdev tries to generate an alias from ACPI and OF data; both lookups
return -ENODEV , which serdev incorrectly propagates as a read failure.
The modalias should instead be readable with empty content, because this
manually created device has no firmware alias. Returning -ENODEV makes sysfs
enumeration fail and causes Checkbox dkms_info_attachment to abort.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Affects: linux (Ubuntu Resolute)
Importance: Undecided
Status: New
** Description changed:
- [Summary]
- Cannot open
/sys/devices/pnp0/00:01/00:01:0/00:01:0.0/serial0/serial0-0/modalias
-
- [Steps to Reproduce]
- 1. Boot into OS
- 2. sudo cat
/sys/devices/pnp0/00:01/00:01:0/00:01:0.0/serial0/serial0-0/modalias
-
- [Expected Result]
- It should be able to open
-
- [Actual Result]
- cat: '/sys/devices/pnp0/00:01/00:01:0/00:01:0.0/serial0/serial0-0/modalias':
No such device
+ The Dell UART backlight driver creates a serial0-0 serdev device without
ACPI or Device Tree firmware metadata. When userspace reads its modalias
sysfs file, serdev tries to generate an alias from ACPI and OF data; both
lookups
+ return -ENODEV , which serdev incorrectly propagates as a read failure.
+
+ The modalias should instead be readable with empty content, because this
manually created device has no firmware alias. Returning -ENODEV makes sysfs
enumeration fail and causes Checkbox dkms_info_attachment to abort.
** Also affects: linux (Ubuntu Resolute)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2171046
Title:
Firmware-less serdev device returns ENODEV for modalias, breaking
sysfs enumeration
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