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SubjectRe: [RFC PATCH 15/33] move segment checks to subarch
Arjan van de Ven wrote:
> On Tue, 2006-07-18 at 00:00 -0700, Chris Wright wrote:
>
>> plain text document attachment (i386-segments)
>> We allow for the fact that the guest kernel may not run in ring 0.
>> This requires some abstraction in a few places when setting %cs or
>> checking privilege level (user vs kernel).
>>
>
>
>> - regs.xcs = __KERNEL_CS;
>> + regs.xcs = get_kernel_cs();
>>
>
> Hi,
>
> wouldn't this patch be simpler if __KERNEL_CS just became the macro that
> currently is get_kernel_cs() for the XEN case? then code like this
> doesn't need changing at all...
>

The tradeoff is that then you can't use __KERNEL_CS is assembler code,
and it is used in entry.S to detect NMI / debug trap workarounds - which
don't actually need to be paravirtualized, as it is easier to hide the
nasty cases which cause those side effects.

Zach
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