Re: Updated version of RD/WR FS/GS BASE patchkit

[Andi Kleen]

> No.  My objection is that there needs to be an explicit statement what
> the semantics are.  If the agreed-upon semantics are "undefined
> behavior if GS != 0 and GSBASE doesn't match the descriptor", so be
> it, but this needs to be a conscious decision and needs to be weighed
> against the alternatives.

Documentation/x86/fsgs.txt already has this statement:

>>>
Another requirement is that the FS or GS selector has to be zero
(is normally true unless changed explicitly). When it is non-zero
the context switch assumes the bases were loaded through the LDT/GDT,
and will reload that.
<<<

Is that sufficient?

> 
> The actual implementation details are just details.  They need to
> match the intended semantics, of course.

I believe my implementation matches the paragraph above.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.