Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Static Interrupt Mappings

Static Interrupt Mappings

For the ISR to determine a correct SYSINTR return value there must be a mapping between the IRQ and the SYSINTR, which can be hardcoded into the OAL. The Bsp_cfg.h file for the Device Emulator BSP demonstrates how to define a SYSINTR value in the OAL for a target device relative to the SYSINTR_FIRMWARE value. If you want to define additional identifiers in your OAL for a custom target device, keep in mind that the kernel reserves all values below SYSINTR_FIRMWARE for future use and the maximum value should be less than SYSINTR_MAXIMUM.

To add a mapping of static SYSINTR values to IRQs on a target device, you can call the OALIntrStaticTranslate function during system initialization. For example, the Device Emulator BSP calls OALIntrStaticTranslate in the BSPIntrInit function to register a custom SYSINTR value for the built-in Open Host Controller Interface (OHCI) in the kernel's interrupt mapping arrays (g_oalSysIntr2Irq and g_oalIrq2SysIntr). However, static SYSINTR values and mappings are not a common way to associate IRQs with SYSINTRs because it is difficult and requires OAL code changes to implement custom interrupt handling. Static SYSINTR values are typically used for core hardware components of a target device where there is no explicit device driver and the ISR resides in the OAL.

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