Re: [PATCH] KVM: Remove arch specific components from the general code

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Gregory Haskins wrote:
> On Thu, 2007-07-26 at 15:33 +0300, Avi Kivity wrote:
>
>   
>> The suggestion I liked best (Anthony's) was
>>
>>   struct vmx_vcpu {
>>         struct kvm_vcpu vcpu;
>>         void *vmcs;
>>         // other vmx-specific data
>>    };
>>
>> to move from a kvm_vcpu to a vmx_vcpu, you use container_of() (inside 
>> your vmx() inline).  Look ma, no pointers!
>>     
>
> Hmm..well, you still have pointers.  The advantage is that they are
> implicitly maintained, but now you have to do pointer arithmetic to
> compute it. :(  I personally would probably rather have the explicit
> management code than the run-time overhead....
>   

Well, the pointer arithmetic consists of adding or subtracting zero, 
which gcc luckily knows how to deal with.

It's the equivalent of C++ inheritance; no overhead at all.

> But alas, the rest of Linux is moving in this direction as well, so I
> think this recommendation makes a lot of sense.  Note that it
> complicates the initialization code a little bit, but its not a big
> deal.  I will incorporate this into the next spin.
>
>
>   
>> Too many people are touching this area without coordinating (and one 
>> patch will invalidate all the rest).  
>>     
>
> Ah, I wasn't aware of this.  Who else is working on it?  
>
>   

Paul Turner did something much like yours, and Rusty is working on 
unraveling the vcpu array, which is complementary to this work.


-- 
error compiling committee.c: too many arguments to function


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