[Lguest] [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes

[Andi Kleen]

On Thu, Nov 27, 2008 at 12:13:43PM +0200, Avi Kivity wrote:
> H. Peter Anvin wrote:
> >
> >>I suspect we could get it down to three bytes, by sharing the last 
> >>byte of the four-byte call sequence with the first byte of the next:
> >>
> >> 66 e8 ff 66 e8 fc 66 e8 f9 66 e8 f6 ...
> >>
> >>Every three bytes a new stub begins; it's a four-byte call to offset 
> >>0x6703 relative to the beginning of the first stub.
> >>
> >>Can anyone better 24 bits/stub?
> >
> >On the entirely silly level...
> >
> >CC xx
> 
> Nice.  Can actually go to zero, by pointing the IDT at (unmapped_area + 
> vector), and deducing the vector in the page fault handler from cr2.

That would be still one byte, otherwise you wouldn't get a unique index.

-Andi

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ak at linux.intel.com