Re: [PATCH kernel 4/6] powerpc/powernv: Add indirect levels to it_userspace

2018-06-11 Thread David Gibson
On Fri, Jun 08, 2018 at 03:46:31PM +1000, Alexey Kardashevskiy wrote: > We want to support sparse memory and therefore huge chunks of DMA windows > do not need to be mapped. If a DMA window big enough to require 2 or more > indirect levels, and a DMA window is used to map all RAM (which is > a defa

[PATCH kernel 4/6] powerpc/powernv: Add indirect levels to it_userspace

2018-06-07 Thread Alexey Kardashevskiy
We want to support sparse memory and therefore huge chunks of DMA windows do not need to be mapped. If a DMA window big enough to require 2 or more indirect levels, and a DMA window is used to map all RAM (which is a default case for 64bit window), we can actually save some memory by not allocation