only one CPU detected on HP Gen9
When booting on a HP Gen9, the system will detect only one CPU:
Mar 22 04:56:56 myhost unix: [ID 608849 kern.notice] NOTICE: System detected 36 cpus, but only 1 cpu(s) were enabled during boot. Mar 22 04:56:56 myhost unix: [ID 458440 kern.notice] NOTICE: Use "boot-ncpus" parameter to enable more CPU(s). See eeprom(1M).
Disabling x2apic makes it work.
This is because of a ACPI spec violation by the HP BIOS: The MADT table is supposed to use local APIC structured for all CPUs with APIC IDs less than 255, and X2APIC structures only for those that use APIC ID 255 and above. The HP BIOS instead only uses X2APIC structures for all CPUs, regardless of the APIC ID.
This will need a workaround in apix (acpi_probe() in mp_platform_common.c) and acpidev (in acpidev_cpu.c).
Updated by Electric Monk about 5 years ago
- Status changed from New to Closed
- % Done changed from 0 to 100
commit c67b1bdc42c9c8c104b7c28c14222c006aa56b1e Author: Hans Rosenfeld <firstname.lastname@example.org> Date: 2016-03-30T22:33:46.000Z 6807 only one CPU detected on HP Gen9 Reviewed by: Josef 'Jeff' Sipek <email@example.com> Reviewed by: Dan McDonald <firstname.lastname@example.org> Reviewed by: Garrett D'Amore <email@example.com> Approved by: Robert Mustacchi <firstname.lastname@example.org>