Re: [Xen-devel] [PATCH] blkif.h: document scsi/0x12/0x<NN> node

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Bob Liu [mailto:bob.liu@xxxxxxxxxx]
> Sent: 23 March 2016 11:48
> To: xen-devel@xxxxxxxxxxxxx
> Cc: Paul Durrant; Ian Jackson; konrad.wilk@xxxxxxxxxx; jgross@xxxxxxxx;
> Roger Pau Monne; annie.li@xxxxxxxxxx; David Vrabel; Bob Liu
> Subject: [PATCH] blkif.h: document scsi/0x12/0x<NN> node
> 
> This patch documents a xenstore node which is used by XENVBD Windows
> PV
> driver.
> 
> The use case is that XenServer may have OEM specific storage backends and
> there is requirement to run OEM software in guest which relied on VPD
> information supplied by the storages.
> Adding a node to xenstore is the easiest way to get this VPD information
> from
> the backend into guest where XENVBD Windows PV driver can get INQUIRY
> VPD data
> from this node and return to OEM software.
> 
> Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
> ---
>  xen/include/public/io/blkif.h |   24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h
> index 99f0326..afbcbff 100644
> --- a/xen/include/public/io/blkif.h
> +++ b/xen/include/public/io/blkif.h
> @@ -182,6 +182,30 @@
>   *      backend driver paired with a LIFO queue in the frontend will
>   *      allow us to have better performance in this scenario.
>   *
> + * scsi/0x12/0x<NN>
> + *   Values: base64 encoded string
> + *
> + *   This optional node contains SCSI INQUIRY VPD information.
> + *   <NN> is the hexadecimal representation of the VPD page code.
> + *   Currently only XENVBD Windows PV driver is using this node.
> + *
> + *   A frontend e.g XENVBD Windows PV driver which represents a Xen
> VBD to
> + *   its containing operating system as a (virtual) SCSI target may return
> the

s/target/LUN

> + *   specified data in response to INQUIRY commands from its containing
> OS.

I think we can safely say "containing OS" is Windows.

> + *
> + *   A frontend which supports this feature must return the backend-
> specified
> + *   data for every INQUIRY command with the EVPD bit set.
> + *   For EVPD=1 INQUIRY commands where the corresponding xenstore
> node
> + *   does not exist, the frontend must report (to its containing OS) an
> + *   appropriate failure condition.

Not necessarily. Page 0x80 is compulsory in the T10 SPC spec so it has to be 
synthesized in the absence of data in xenstore.

> + *
> + *   A frontend which does not support this feature just disregard these
> + *   xenstore nodes.
> + *
> + *   The data of this string node is base64 encoded. Base64 is a group of
> + *   similar binary-to-text encoding schemes that represent binary data in
> an
> + *   ASCII string format by translating it into a radix-64 representation.

Do we need to explain what base64 is?

  Paul

> + *
>   *----------------------- Request Transport Parameters 
> ------------------------
>   *
>   * max-ring-page-order
> --
> 1.7.10.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel