Hi Wen and Laurent, > >> Also regarding to the VCMM (Virtual Contiguous Memory Manager) or CMA, is >> it also an option? > > I'm not sure about VCMM, it seems to be an attempt to unify memory management > across IOMMUs and system MMU. I don't think you need to worry about it now, > IOMMU should be enough for your needs. > > CMA, as its name implies, is a contiguous memory allocator. As your ISP has an > IOMMU, you don't need to allocate contiguous memory, so CMA isn't useful for > your hardware. > VCM(aka. VCMM) is a virtual memory (device memory) allocator and manager when a system has multiple MMUs. Since physical memory allocation (and virtual memory allocation also) for processes by O/S is not suitable for peripheral devices, VCM separates allocating physical memory and virtual memory. It also gives you chances to override the default behavior of the allocators. If you concern about device memory management with IOMMU, I think VCM is one of good options even though a system has only one IOMMU to deal with. It is not merged into the Linux kernel because applications of VCM is very restricted and just few people are interested in it. KyongHo. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
