Unable to boot 64bit Linux, CPU does not support long mode

[dejavu]

..Use a 32bit distribution.

I just bought macbookpro a week ago, when I try to boot 64 bit Linux, I got message as "Your cpu does not support long mode. Use 32 bit distribution"
then I restart mac host and press 6 + 4 to brought into 64 kernel. I was able to start 64bit guest linux. My friend bought same mac 4 months ago, he can start 64bit Linux without putting 64kernel on his kernel. I attach logs for comparison.
Is there any missing configuration I needed to boot 64bit on my host?

[rpmurray]

Did you enable VT-x in Settings > System > Acceleration?

The unable_boot_64guestlinux_from_32bithost.log has the following line:

00:00:01.541 HWACCM: 32-bit guests supported

In the 32bitmac_boot64bit_guest_with_success.log it says:

00:00:01.330 HWACCM: 32-bit and 64-bit guests supported.

[dejavu]

From Setting--
Options checked are
Motherboard : Enable IO APIC
Processor : Enable PAE/NX
Acceleration : Enable VT-x/AMD-v

Enable VT-x/AMD-v option are by default checked I think, because I don't remember to change it, but I do remember changing "Enable IO APIC" after I boot mac host to 64bit and I don't see message "CPU does not support", I got different message, then I checked IO APIC, OS installation on guest can be finished.

Any other settings need to be changed? probably from host itself?

[ukchucktown]

Yes, you can force the mac to always boot in 64-bit mode by editing a plist file. You need to edit an XML file with TextEdit then reboot.

1. Launch TextEdit
2. Open the file named /Library/Preferences/SystemConfiguration/com.apple.Boot.plist
3. add arch=x86_64 to the Kernel Flags string:

…
<key>Kernel</key>
<string>mach_kernel</string>
<key>Kernel Flags</key>
<string>arch=x86_64</string>

To return to 32-bit mode replace x86_64 with i386.

[dejavu]

Hey.. That's a good tip, thanks might want to test it.
But for 32bit issue.I wonder what others use with their vbox.
Do you always boot to 64host before starting 64guest?
Last night I try to boot 64host, and already have a compability issue with other application

Is there any workaround for boot 64guest from 32host mac?