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貌似作者对MP spec 为PIC 和APIC 共存的平台规定了三种模式中的Virtual Wire Mode模式的理解有一些问题,楼主在pdf文档中描述如下:
如图虚线,外部中断通过PIC 连接的IOAPIC 管脚,最终到达BSP。当然,连接PIC的这个管脚需要被配置成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.
根据MP spec,应该是Local APIC的LINTIN0脚要配置为ExtINT 模式。另外,对于Virtual Wire Mode模式,原文描述了两种接线方式,一种是PIC接IO-APIC,然后接BSP的Local APIC,另外一种是PIC直接接到BSP的Local APIC的LINTIN0脚。
另外,对Symmetric I/O Mode描述也有不准确的地方,楼主在pdf中描述如下:
一个要求,进入APIC 模式后要将PIC 的所有管脚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.
根据MP spec,应该是屏蔽8259A的所有中断线或者将8259A与I/O APIC混合使用。
[ 本帖最后由 fox144215 于 2009-11-19 09:26 编辑 ] |
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