https://bugzilla.kernel.org/show_bug.cgi?id=13170

--- Comment #64 from dentament l_done@tiscali.it 2011-08-19 11:08:25 --- Hi, I boot with 2 cpus, acpi and everything working on ubuntu 10.04 using grub 1.99 compiled following these instructions: https://help.ubuntu.com/community/UEFIBooting and with this grub.cfg:

----- insmod efi_gop menuentry "Ubuntu Linux Lucid 2.6.32-33-generic" { set root='(hd0,3)' linux /boot/vmlinuz-2.6.32-33-generic root=/dev/sda3 video=efifb ro splash initrd /boot/initrd.img-2.6.32-33-generic } -----

But there's still a problem with this method (tried with various versions of grub-efi): although it may seem the cpus do frequency switching allright, they actually always work at their minimum speed. See: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/669865