Ubuntu
linux package

  1. Bug #1398497
  2. Comment #31

Comment 31 for bug 1398497

Revision history for this message
Rafael David Tinoco (rafaeldtinoco) wrote :

Dave,

This message is being given to let you know that your BIOS (EFI/firmware/..) is "asking" the OS to NOT USE x2apic (and this happens on HP Proliant Servers). This is because, before Gen7, Proliant servers did not support X2APIC (a new Programmable Interrupt Controller) and had to operate into "XAPIC"/"APIC" compatible mode (even if their CPU supported X2APIC).

For Proliant Servers >= Gen8 you can say to Linux to "ignore" this request from firmware. To do that you change

GRUB_CMDLINE_LINUX_DEFAULT="..." to
GRUB_CMDLINE_LINUX_DEFAULT="... intremap=no_x2apic_optout"

inside /etc/default/grub and run "update-grub" command (rebooting your server later on).

This is because Gen8 are X2APIC capable but the firmware still asks OS not to enable it (as I was told by HP).

If you use HP Proliant Servers < Gen8 you have to use:

"nox2apic intermap=off"

For not having problems regarding IRQ handling, deactivating x2apic.

Note that if you are using HP Proliant Servers you have to be aware of the following bug also:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1318551

adding "intel_idle.max_cstate=0" to the cmdline also.