Re: NVME hotplug support ?

[Klaus Jensen <its@irrelevant.dk>]

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On Jan 23 10:59, Damien Hedde wrote:
> Hi all,
> 
> We are currently looking into hotplugging nvme devices and it is currently not possible:
> When nvme was introduced 2 years ago, the feature was disabled.
> > commit cc6fb6bc506e6c47ed604fcb7b7413dff0b7d845
> > Author: Klaus Jensen 
> > Date:   Tue Jul 6 10:48:40 2021 +0200
> >
> >    hw/nvme: mark nvme-subsys non-hotpluggable
> >    
> >    We currently lack the infrastructure to handle subsystem hotplugging, so
> >    disable it.
> 
> Do someone know what's lacking or anyone have some tips/idea of what we should develop to add the support ?
> 
> Regards,
> --
> Damien 
> 

That's not entirely true.

The *subsystem* is non-hotpluggable, but individual controllers can be
hotplugged. Even into an existing subsystem.

However, you cannot hotplug pci devices unless you set up a pcie root
port. Say,

  -device "pcie-root-port,id=pcie_root_port0,chassis=1,slot=0"
  -device "nvme,id=nvme0,serial=nvme0,bus=pcie_root_port0"

nvme0 can then be removed with device_del and added back as a new device
with device_add.

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