Re: [PATCH] x86_64: check if Tom2 is enabled

[Andi Kleen]

> 
> Actually, I think it depends on the specific MSR - some use the halves 
> for different data, whereas others treat it as a large 64-bit object.

Even if there are different fields in there it is still much cleaner
and simpler if there is only a single number to manipulate.

> Ironically enough, the way the MSR interfaces were carried into the 
> 64-bit world makes the situation worse on 64 bits; edx:eax is the common 
> way to represent a 64-bit value on 32 bits.

It's merely an implementation detail of the instruction. But even on 32bit
there is about zero reason to expose that to C code. rdmsr/wrmsr et.al. should
have been defined as 64bit only interface in Linux from day zero.

-Andi
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