[SPDK] Re: NVMe devices with CMB

On Nov  4 22:39, Kit Chow wrote:
> Hi Benjamin,
> 
> I found the following qemu nvme blog - http://blog.frankenmichl.de/2018/02/13/add-nvme-device-to-vm/
> 
> Following the instructions, I get the NVMe device listed below with a bar4 size of 4K. Is this the CMB and is it large enough for small p2p copies?
> 

Hi Kit,

You need to specifically enable the CMB with the `cmb_size_mb`
parameters (argument in MBs).

  -device "nvme,id=nvme0,serial=deadbeef,cmb_size_mb=64"

Looks like you are using a pretty old version of QEMU. In current
versions the CMB is exclusively using BAR 4 - I think what you are
seeing is an older version where the MSI-X tables were in BAR4.

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