Date: Sat, 01 Nov 2003 14:40:50 -0800 From: Sean McNeil <sean@mcneil.com> To: freebsd-hackers@freebsd.org Subject: question about user space addressed, mmap, and getting phys address Message-ID: <1067726450.65578.6.camel@blue.mcneil.com>
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Hi everyone, Sorry I am not on the list, but I was hoping someone here might be able to help me. I have a design that I cannot change that does the following: 1) Calls mmap on a chunk of memory that the device driver uses to DMA to a video decoder. 2) This chunk of memory is treated as several DMA buffers. There is an ioctl setup to indicate when a section of that memory is being used and when it is freed (usage count). I need to take the address from the mmap, add an offset, send it through an ioctl, and then relate it back to the physical address that it was originally mapped from. Unfortunately, the address I get from the ioctl is a user-space address and when I use vtophys I get back 0. Is there some other mechanism to convert a user-space address to a physical address? Any and all help will be greatly appreciated. Thanks in advance, Sean
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