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貌似作者對MP spec 為PIC 和APIC 共存的平臺規(guī)定了三種模式中的Virtual Wire Mode模式的理解有一些問題，樓主在pdf文檔中描述如下：
如圖虛線，外部中斷通過PIC 連接的IOAPIC 管腳，最終到達BSP。當然，連接PIC的這個管腳需要被配置成ExtINT 模式。
MP spec原文如下：
In Virtual Wire Mode, as shown in Figure 3-3, the 8259A-equivalent PIC fields all interrupts, and the local APIC of the BSP becomes a virtual wire, which delivers interrupts from the PIC to the BSP via the local APIC’s local interrupt 0 (LINTIN0). The LINTIN0 pin of the local APIC is programmed as ExtINT, specifying to the APIC that the PIC is to serve as an external interrupt controller. Whenever the local APIC finds that a particular interrupt is of type ExtINT, it asserts the ExtINTA transaction along with the PINT interrupt to the processor. In this case, the I/O APIC is not used.
根據(jù)MP spec，應(yīng)該是Local APIC的LINTIN0腳要配置為ExtINT 模式。另外，對于Virtual Wire Mode模式，原文描述了兩種接線方式，一種是PIC接IO-APIC，然后接BSP的Local APIC，另外一種是PIC直接接到BSP的Local APIC的LINTIN0腳。
另外，對Symmetric I/O Mode描述也有不準確的地方，樓主在pdf中描述如下：
一個要求，進入APIC 模式后要將PIC 的所有管腳mask 掉。
而MP spec原文如下：
Some MP operating systems operate in Symmetric I/O Mode. This mode requires at least one I/O APIC to operate. In this mode, I/O interrupts are generated by the I/O APIC. All 8259 interrupt lines are either masked or work together with the I/O APIC in a mixed mode.
根據(jù)MP spec，應(yīng)該是屏蔽8259A的所有中斷線或者將8259A與I/O APIC混合使用。
[ 本帖最后由 fox144215 于 2009-11-19 09:26 編輯 ] |
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樓主: zx_wing
發(fā)表于 2009-07-28 11:20
