On 06/27/2012 06:44 AM, Hiroshi Doyu wrote: ... > I think that there are 2 cases: > > (1) discontiguous memory with IOMMU > (2) contiguous memory without IOMMU(called "carveout" in general?) ... > For (2), although memory is mostly anonymous one, we may need to know > how much to allocate, where we only need "size". This size is not from > h/w feature, but it depends on the system load/usage. So I think that > this size can be passed from kernel command line? For exmaple, we can > specify how much contiguous memory is necessary with putting > "coherent_pool=??M" in the kernel command line as below: > > coherent_pool=nn[KMG] [ARM,KNL] > Sets the size of memory pool for coherent, atomic dma > allocations. I guess if that's the standard way of initializing CMA, then that's fine. It'd be nice if there was a way to specify that from the DT too; that way the user/distro/bootloader constructing the kernel command-line wouldn't have to remember to add "random" (potentially Tegra-/board-specific) extra arguments onto the command-line; the Tegra command-line in the upstream kernel is quite clean right now, especially compare to the enormous number of options we require downstream:-( -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
