On 1/22/19 9:23 PM, Sumit Semwal wrote: > Hello everyone, > > (Thanks to Dan for letting me know my last email got corrupted :/ - > resending it here) > Hmm, this one seems a bit messed up also (Thunderbird doesn't seem to like it at least). [snip] > - from dma-buf PoV, ION is an exporter of dma-buf buffers, for its users > that have specific requirements. > This is what I'm hoping to change up a little bit, Ion shouldn't be the exporter, its heaps should be the exporters (manage the dma_buf_ops), Ion would only do advertising of available heaps and allow allocating DMA-BUFs from them. IMO that would clear up the other discussions going on right now about how Ion should handle different dma-buf syncing tasks, it simply wouldn't :). Plus Ion core gets slimmed down, maybe even enough for destaging.. >> I haven't either, which is a shame as it allows for some really useful >> management strategies for shared memory resources. I'm working on one >> such case right now, maybe I'll get to be the first to upstream one :) >> > Yes, it would, and great that you're looking to be the first one to do it :) > >> > I wasn't aware that CPU access before first device access was >> > considered an abuse of the API - it seems like a valid thing to want >> > to do. >> > >> >> That's just it, I don't know if it is an abuse of API, I'm trying to get >> some clarity on that. If we do want to allow early CPU access then that >> seems to be in contrast to the idea of deferred allocation until first >> device map, what is supposed to backing the buffer if no devices have >> attached or mapped yet? Just some system memory followed by migration on >> the first attach to the proper backing? Seems too time wasteful to be >> have a valid use. >> >> Maybe it should be up to the exporter if early CPU access is allowed? >> >> I'm hoping someone with authority over the DMA-BUF framework can clarify >> original intentions here. >> > > I suppose dma-buf as a framework can't know or decide what the exporter > wants or can do - whether the exporter wants to use it for 'only > zero-copy', or do some intelligent things behind the scene, I think > should be best left to the exporter. > > Hope this helps, Yes, these inputs are very helpful, thanks, Andrew > Sumit. > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
