Re: [Xen-devel] [RFC PATCH] xen-block: introduces extra request to pass-through SCSI commands

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
> Konrad Rzeszutek Wilk
> Sent: 03 March 2016 14:07
> To: Juergen Gross; Ian Jackson; Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxx; jbeulich@xxxxxxxx; Roger Pau Monne
> Subject: Re: [Xen-devel] [RFC PATCH] xen-block: introduces extra request to
> pass-through SCSI commands
> 
> On March 3, 2016 7:25:11 AM EST, Juergen Gross <jgross@xxxxxxxx> wrote:
> >On 03/03/16 13:03, Ian Jackson wrote:
> >> Paul Durrant writes ("RE: [RFC PATCH] xen-block: introduces extra
> >request to pass-through SCSI commands"):
> >>> Actually, that's quite desirable. The existing driver is actually a
> >>> SCSI HBA driver (because that's all you can write is you use thr
> >>> Windows STORPORT wrapper... which you need to if you want to pass
> >>> WHQL) so making it use a PV scsi protocol would probably make it
> >>> smaller since all the scsi <-> blkif translation code could be
> >>> ripped out and all the stuff to synthesize INQUIRY responses based
> >>> on vbd data in xenstore could go away too.
> >>
> 
> Wait a minute? You have that in the driver? Is this documented somewhere?
> Did I miss this in blkif.h?
> 

Yes, the Windows XENVBD driver has a whole load of code for synthesizing 
INQUIRY responses since that's how Windows probes for disks. There's nothing in 
blkif.h for any of this though since it’s an implementation detail of the 
Windows frontend. However, if you want to take a look, go to 
http://xenbits.xen.org/gitweb/?p=pvdrivers/win/xenvbd.git;a=blob;f=src/xenvbd/pdoinquiry.c.
 There's even code in there for base64 decoding VPD pages from xenstore! 
(That's a XenServer implementation artefact... I'm not recommending it as a way 
forward ;-))

  Paul

> 
> >> Do non-Linux hosts have something like LIO ?
> >
> >Are there any pvSCSI backends other than the one in Linux?
> >
> 
> Not that I know off.
> 
> 
> 
> 
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