Kernel space is flagged in the page tables as exclusive to privileged code (ring 2 or lower), hence a page fault is triggered if user-mode programs try to touch it.

系统内核所使用的内存空间通过特权码（privileged code，2级或者更低）来标记，以防止用户模式的程序访问到内核空间而发生页面错误。

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The ring 2 stack is in use.

第2环堆栈已被占用。

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The utility model relates to a cross axle universal coupling, which is characterized in that a cross axle head is composed of a cross axle ring (2) and four axle extensions (3).

一种新型的十字轴式万向联轴器，其特征在于十字轴头是由十字轴环(2)与四个轴伸(3)所组成。

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The researchers' calculations place the dust in a ring 2.5 astronomical units from Zeta Lep.

ECONOMIST: Planetary formation

With CES 2013 coming to a frigid conclusion here in Las Vegas, we moseyed our way to the Genius booth and went thumbs-on with the Ring Presenter and the Ring Mouse 2.

ENGADGET

In fact, a recent study conducted by German researchers using tree ring data reveals that 2, 000 years ago Romans wore cool togas with good reason.

FORBES: Gullible Warming: A Contrived Crisis That Is Too Good To Waste