Re: [PATCH 02/11] Add "handle page fault" PV helper.

[Avi Kivity]

On 11/03/2009 01:35 AM, Rik van Riel wrote:
> > We can't add an exception vector since all the existing ones are either
> > taken or reserved.
>
>
> I believe some are reserved for operating system use.

Table 6-1 says:

  9 |  | Coprocessor Segment Overrun (reserved)  |  Fault |  No  | 
Floating-point instruction.2
  15 |  â |  (Intel reserved. Do not use.) |   | No |
  20-31 |  â | Intel reserved. Do not use.  |
  32-255 |  â  | User Defined (Non-reserved) Interrupts |  Interrupt  
|   | External interrupt or INT n instruction.

So we can only use 32-255, but these are not fault-like exceptions that 
can be delivered with interrupts disabled.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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