Re: Setting nx bit in virtual CPU

[Avi Kivity <avi@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 512 bytes --]

On 04/07/2010 01:31 AM, Richard Simpson wrote:
>
>> 2.6.27 should be plenty fine for nx.  Really the important bit is that
>> the host kernel has nx enabled.  Can you check if that is so?
>>
>>      
> Umm, could you give me a clue about how to do that.  It is some time
> since I configured the host kernel, but I do have a /proc/config.gz.
> Could I check by looking in that?
>    

The attached script should verify it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


[-- Attachment #2: check-nx --]
[-- Type: text/plain, Size: 497 bytes --]

#!/usr/bin/python

class msr(object):
    def __init__(self):
        try:
            self.f = file('/dev/cpu/0/msr')
        except:
            self.f = file('/dev/msr0')
    def read(self, index, default = None):
        import struct
        self.f.seek(index)
        try:
            return struct.unpack('Q', self.f.read(8))[0]
        except:
            return default

efer = msr().read(0xc0000080, 0)
nx = (efer >> 11) & 1

if nx:
   print 'nx: enabled'
else:
    print 'nx: disabled'