[PATCH] nvmet: Add support for HOST_ID feature.

[Verkamp, Daniel]

> -----Original Message-----
> From: Linux-nvme [mailto:linux-nvme-bounces at lists.infradead.org] On Behalf
> Of Sagi Grimberg
> Sent: Monday, August 28, 2017 6:44 AM
> To: Omri Mann <omri at excelero.com>; linux-nvme at lists.infradead.org
> Cc: Mike Christie <mchristi at redhat.com>
> Subject: Re: [PATCH] nvmet: Add support for HOST_ID feature.
> 
> > diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> > index e3b244c..841f35d 100644
> > --- a/drivers/nvme/target/nvmet.h
> > +++ b/drivers/nvme/target/nvmet.h
> > @@ -132,6 +132,7 @@ struct nvmet_ctrl {
> >
> >   	char			subsysnqn[NVMF_NQN_FIELD_LEN];
> >   	char			hostnqn[NVMF_NQN_FIELD_LEN];
> > +	u64			host_id;
> 
> I'd move it to the first cacheline given it will be accessed
> in the hot path.
> 
> Other than that, looks fine,
> 
> Reviewed-by: Sagi Grimberg <sagi at grimberg.me>

The specification says that NVMe-oF must use a 128-bit host ID - from NVMe 1.3, 5.21.1.19.2:

"The Host Identifier is a mandatory feature in NVMe over Fabrics.  The Host Identifier shall be an extended 128-bit Host Identifier." 

The target should also check the EXHID bit in the Get Features - Host Identifier command.

Thanks,
-- Daniel Verkamp