<Snip> >> the details, but I think the strategy were to pass a parameter during >> kernel boot, for it to reserve some amount of memory that would later be >> claimed by the V4L device. > >It's actually a pretty common strategy for embedded hardware (the "general- >purpose machine" case doesn't - for now - make much sense on an OMAP >processor >for instance). A memory chunk would be reserved at boot time at the end of >the >physical memory by passing the mem= parameter to the kernel. Video >applications would then mmap() /dev/mem to access that memory (I'd have to >check the details on that one, that's from my memory), and pass the pointer >the the v4l2 driver using userptr I/O. This requires root privileges, and >people usually don't care about that when the final application is a camera >(usually embedded in some device like a media player, an IP camera, ...). > >Regards, Yes. This is exactly what we are doing in the case of davinci processors. We have a kernel module that uses memory from the end of SDRAM space and mmap it to application through a set of APIs. They allocate contiguous memory pools and return the same to application through IOCTLs. I have tested vpfe capture using this approach (but yet to push the same to v4l2 community for review). The same approach may be used across other platforms as well. So doesn't it make sense to add this kernel module to the kernel tree so that everyone can use it?
Murali > >Laurent Pinchart > >-- >To unsubscribe from this list: send the line "unsubscribe linux-media" in >the body of a message to majord...@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html
