On 10/05/2015 03:11 AM, Benjamin Gaignard wrote: > version 4 changes: > - rebased on kernel 4.3-rc3 > - fix missing EXPORT_SYMBOL for smaf_create_handle() > > version 3 changes: > - Remove ioctl for allocator selection instead provide the name of > the targeted allocator with allocation request. > Selecting allocator from userland isn't the prefered way of working > but is needed when the first user of the buffer is a software component. > - Fix issues in case of error while creating smaf handle. > - Fix module license. > - Update libsmaf and tests to care of the SMAF API evolution > https://git.linaro.org/people/benjamin.gaignard/libsmaf.git > > version 2 changes: > - Add one ioctl to allow allocator selection from userspace. > This is required for the uses case where the first user of > the buffer is a software IP which can't perform dma_buf attachement. > - Add name and ranking to allocator structure to be able to sort them. > - Create a tiny library to test SMAF: > https://git.linaro.org/people/benjamin.gaignard/libsmaf.git > - Fix one issue when try to secure buffer without secure module registered > > The outcome of the previous RFC about how do secure data path was the need > of a secure memory allocator (https://lkml.org/lkml/2015/5/5/551) > > SMAF goal is to provide a framework that allow allocating and securing > memory by using dma_buf. Each platform have it own way to perform those two > features so SMAF design allow to register helper modules to perform them. > > To be sure to select the best allocation method for devices SMAF implement > deferred allocation mechanism: memory allocation is only done when the first > device effectively required it. > Allocator modules have to implement a match() to let SMAF know if they are > compatibles with devices needs. > This patch set provide an example of allocator module which use > dma_{alloc/free/mmap}_attrs() and check if at least one device have > coherent_dma_mask set to DMA_BIT_MASK(32) in match function. > I have named smaf-cma.c like it is done for drm_gem_cma_helper.c even if > a better name could be found for this file. > > Secure modules are responsibles of granting and revoking devices access rights > on the memory. Secure module is also called to check if CPU map memory into > kernel and user address spaces. > An example of secure module implementation can be found here: > http://git.linaro.org/people/benjamin.gaignard/optee-sdp.git > This code isn't yet part of the patch set because it depends on generic TEE > which is still under discussion (https://lwn.net/Articles/644646/) > > For allocation part of SMAF code I get inspirated by Sumit Semwal work about > constraint aware allocator. >
Overall I like the abstraction. Do you have a use case in mind right now for the best allocation method? Some of the classic examples (mmu vs. no mmu) are gradually becoming less relevant as the systems have evolved. I was discussing constraints with Sumit w.r.t. Ion at plumbers so I'm curious about your uses. Thanks, Laura
