Hi Hari, You are right. What we need is virtual address.
Currently we alloc pages (alloc_pages()) for any request. Store those pages for an image buffer into a list. We also manage the virtual address for ISP by ourself (the range from 0 to 4GB) and the page table for our MMU which is independent to system MMU page table. Thanks Wen >-----Original Message----- >From: Kanigeri, Hari K >Sent: 2011年2月9日 15:22 >To: Iyer, Sundar; Wang, Wen W; Yang, Jianwei; linux-media@vger.kernel.org; >umg-meego-handset-ker...@umglistsvr.jf.intel.com >Cc: Jozef Kruger >Subject: RE: Memory allocation in Video4Linux > > > >> -----Original Message----- >> From: umg-meego-handset-kernel-boun...@umglistsvr.jf.intel.com >> [mailto:umg-meego-handset-kernel-boun...@umglistsvr.jf.intel.com] On >> Behalf Of Iyer, Sundar >> Sent: Wednesday, February 09, 2011 12:20 PM >> To: Wang, Wen W; Yang, Jianwei; linux-media@vger.kernel.org; umg-meego- >> handset-ker...@umglistsvr.jf.intel.com >> Cc: Jozef Kruger >> Subject: Re: [Umg-meego-handset-kernel] Memory allocation in >> Video4Linux >> >> I remember some Continous Memory Allocator (CMA) being iterated down a >> few versions on >> some mailing lists? IIRC, it is also for large buffers and management >> for video IPs. > >I believe CMA is for allocating physically contiguous memory and from what Wen >mentioned he also needs virtual memory management, which the IOMMU will >provide. Please check the open source discussion on CMA, the last I heard CMA >proposal was shot down. >Reference: http://www.spinics.net/lists/linux-media/msg26875.html > >Wen, how are you currently allocating physical memory ? > > >Thank you, >Best regards, >Hari
