rdmsr from userspace

[Rui Paulo]

Andriy Gapon wrote:
> on 17/05/2008 18:37 Rui Paulo said the following:
>> Andriy Gapon wrote:
>>>
>>> It seems that rdmsr instruction can be executed only at the highest 
>>> privilege level and thus is not permitted from userland. Maybe we 
>>> should provide something like Linux /dev/cpu/msr?
>>> I don't like interface of that device, I think that ioctl approach 
>>> would be preferable in this case.
>>> Something like create /dev/cpuN and allow some ioctls on it: 
>>> ioctl(cpu_fd, CPU_RDMSR, arg).
>>> What do you think?
>>>
>>
>> While I think this (devcpu) is good for testing and development, I 
>> prefer having a device driver to handle that specific MSR than a 
>> generic /dev/cpuN where you can issue MSRs.
>> Both for security and reliability reasons.
> 
> What about /dev/pci, /dev/io? Aren't they a precedent?

They are, but, IMHO, we should no longer continue to create this type of 
interfaces.

Regards,
-- 
Rui Paulo