Re: [Qemu-devel] Re: [RFC][PATCH] x86: CS limit checks

[Fabrice Bellard]

[...]
> And then there is the open question how much performance can be gained
> with compile-time optimization for those guests who do use segmentation.

The goal is to optimize the cases where segmentation is not used ! It is 
just an extension of the existing "HF_ADDSEG" optimization.

> The worst case is very roughly about 50% slowdown right now (/w vs. w/o
> -seg-checks). As answered privately, some -no-seg-checks switch could
> remain a useful optimization.

Not sure. I believe most recent OSes (i.e. those where speed really 
matters) have segment registers loaded so that no runtime checks are 
necessary.

Fabrice.