[Mesa-dev] [v4, 21/23] anv/batch_chain: Simplify secondary batch return chaining

[Scott D Phillips]

Jason Ekstrand <jason at jlekstrand.net> writes:

> Previously, we did this weird thing where we left space and an empty
> relocation for use in a hypothetical MI_BATCH_BUFFER_START that would be
> added to the secondary later.  Then, when it came time to chain it into
> the primary, we would back that out and emit an MI_BATCH_BUFFER_START.
> This worked well but it was always a bit hacky, fragile and ugly.  This
> commit instead adds a helper for rewriting the MI_BATCH_BUFFER_START at
> the end of an anv_batch_bo and we use that helper for both batch bo list
> cloning and handling returns from secondaries.  The new helper doesn't
> actually modify the batch in any way but instead just adjusts the
> relocation as needed.

Reviewed-by: Scott D Phillips <scott.d.phillips at intel.com>