Am 30.03.23 um 10:15 schrieb Shashank Sharma:
Hello Pierre-Eric,
[SNIP]
I'm also wondering why the doorbell needs a handle+offset but
other buffers are passed in as virtual addresses?
As you know, doorbell offset here will be an relative offset in this
doorbell page, but the MQD needs the absolute offset on the doorbell
PCI BAR.
So kernel needs both the object as well as relative offset to
calculate absolute offset.
something like: absolute offset = base offset of this doorbell page +
relative offset of this doorbell.
Another much more obvious reason is that the doorbell doesn't have a
virtual address.
At least for GFX the doorbell is used to signal to the hw that new
commands are available. So as long as we don't want a shader to kick of
other work we don't need to map the doorbell into the GPUVM address space.
Christian.
