Re: [Xen-devel] [PATCH] x86_64 trap table fixup

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 4 Jul 2005, at 08:46, Jan Beulich wrote:

> One remark since this code is getting touched now anyway: You appear to
> have taken the same (somewhat broken) approach of handling #BR as Linux
> does. Architecturally, IDT entry 5 should be a DPL=0 one (permitting
> BOUND, but disallowing INT 05); is there any particular reason you want
> to allow INT 05 here (which could get you in conflict with hosting
> Windows, which appears to deal with this the architecture intended 
> way)?
The guest OS is allowed to set the DPL as it wants -- in the case of 
xenlinux we want to retain maximum compatibility with native Linux. 
Other paravirtualised OSes can set the DPL to zero if they wish. In the 
case of Windows, that will only run on VT/SVM hardware anyway, and that 
deals with handling the guest's IDT pretty much automatically, so these 
paravirtual interfaces aren;t used at all.
 -- Keir


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