[dpdk-dev] [PATCH] eal: add option --iso-cmem for external custom memory

[Burakov, Anatoly]

On 15-Oct-19 6:30 AM, Ajit Khaparde wrote:
> From: Rajesh Ravi <rajesh.ravi at broadcom.com>
> 
> Support external custom memory added to heap to be used with vfio with
> --iso-cmem option.Type1 memory mapping was by passed for external memory.
> But an exception is added to allow external custom memory to be used with
> vfio.
> 
> Signed-off-by: Rajesh Ravi <rajesh.ravi at broadcom.com>
> Reviewed-by: Jonathan Richardson <jonathan.richardson at broadcom.com>
> Reviewed-by: Scott Branden <scott.branden at broadcom.com>
> Reviewed-by: Vikram Mysore Prakash <vikram.prakash at broadcom.com>
> Reviewed-by: Ajit Khaparde <ajit.khaparde at broadcom.com>
> ---

Hi,

First of all, what is "iso-cmem"? It doesn't seem to have any defined 
meaning nor any relation to any existing functionality, and it's not 
explained anywhere what is "isolated cmem".

More importantly, why is this necessary? Type1 map only bypasses 
external segments when adding memory at startup - it doesn't stop you 
from calling rte_vfio_dma_map() to map the memory with VFIO when you 
create the segment.

-- 
Thanks,
Anatoly