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Re: [Xen-devel] x86: PIE support and option to extend KASLR randomization

On 09/22/17 09:32, Ingo Molnar wrote:
> BTW., I think things improved with ORC because with ORC we have RBP as an 
> extra 
> register and with PIE we lose RBX - so register pressure in code generation 
> is 
> lower.

We lose EBX on 32 bits, but we don't lose RBX on 64 bits - since x86-64
has RIP-relative addressing there is no need for a dedicated PIC register.

I'm somewhat confused how we can have as much as almost 1% overhead.  I
suspect that we end up making a GOT and maybe even a PLT for no good reason.


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