Hi Laura: >-----邮件原件----- >发件人: Laura Abbott [mailto:labbott@xxxxxxxxxx] >发送时间: 2017年4月18日 0:14 >收件人: Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; sumit.semwal@xxxxxxxxxx >抄送: gregkh@xxxxxxxxxxxxxxxxxxx; arve@xxxxxxxxxxx; >riandrews@xxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxx; >linux-kernel@xxxxxxxxxxxxxxx >主题: Re: Using ion memory for direct-io > >On 04/14/2017 02:18 AM, Zengtao (B) wrote: >> Hi >> >> Currently, the ion mapped to userspace will be forced with VM_IO and >VM_PFNMAP flags. >> When I use the ion memory to do the direct-io, it will fail when >> reaching the get_user_pages, >> >> Back to the VM_IO and VM_PFNMAP flag, there two flags are introduced >> by the remap_pfn_range called by the ion_heap_mmap_user. >> >> From my point of view, all ion memory(cma/vmalloc/system heap) are >> managed by linux vm, it is not reasonable to have the VM_IO and >> VM_PFNMAP flag, but I don't any suitable function to replace the >remap_pfn_range, any suggestions? >> >> Thanks && Regards >> >> Zengtao >> > >The carveout heap is omitted from your list of 'all ion memory'. At one >time, carveout memory was not backed by struct pages so I suspect >this is a holdover from then. This would probably be better served Yes, you are right, I missed the carveout heap which needs the VM_IO and VM_PFNMAP, and I think the carveout heap can implement its own map_user rather then using the common ion_heap_map_user. >by using vm_insert_page and handling higher order pages properly. Your latest patch has remove the the page faulting support, I didn't deep into the reason, but I think this conflicts with the vm_insert_page. > >Thanks, >Laura I tried to use the similar way as the dma framework do(split the page and map_vm_area), but the split will break the ion sg design, maybe we need a new lowlevel map function instead of directly using the remap_pfn_range. Thanks Zengtao _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
