Well a bit background would probably help here.

This is useful because certain applications are hopelessly braindead and pass a CPU which they got from the driver in the first place and which is a pointer to a memory mapped BO back to the driver.

With this IOCTL the driver is capable to handle this case gracefully and use the original BO for example as replacement for an userptr.

Regards,
Christian.

On 03.12.2015 14:02, Zhou, David(ChunMing) wrote: