On 10-4-22 下午11:01, Samuel Thibault wrote: > Samuel Thibault, le Thu 22 Apr 2010 16:51:38 +0200, a écrit : >> Da Zheng, le Thu 22 Apr 2010 22:37:51 +0800, a écrit : >>> So does the driver need to consider about cache coherency problems on PC >>> when >>> interacting with the external device? >> >> Yes (since you can not rely on the BIOS), you need to remap the mmio >> range with cache disabled: INTEL_PTE_NCACHE|INTEL_PTE_WTHRU. This should >> already be done by pmap_enter(). > > And you need to access it using the volatile qualifier. They are not just one or two variables. They are an array of structure variables. Should I define all fields of the structure with volatile qualifier? It's strange. The Linux driver doesn't do so but it definitely works in the Linux kernel.
I use the mem device to allocate MMIO space. I guess INTEL_PTE_NCACHE and INTEL_PTE_WTHRU haven't been set to the MMIO pages, right? Zheng Da
