For segments, the job is split between hardware and microcode. When LD_DESCRIPTOR fires its protection test at 5CD, the Test PLA OR's the A-bit (bit 8 of the descriptor high DWORD) into a temporary register called PROTUN. Then the microcode at PROT_TESTS_PASSED takes over and writes the modified value back to the GDT or LDT in memory:
5. FE 团队“AI 辅助编码标准化”方案
，这一点在heLLoword翻译官方下载中也有详细论述
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I could definitely be reading too much into a six-second social video, but Cook's X post looks to me like the back of a MacBook. The video also shows a person manipulating the Apple logo with their fingers, which, to me, screams "touchscreen."