RE: [PATCH] scsi: storvsc: make INQUIRY response SPC-compliant

[KY Srinivasan]

> -----Original Message-----
> From: Christoph Hellwig [mailto:hch@xxxxxxxxxxxxx]
> Sent: Friday, July 3, 2015 9:19 AM
> To: Vitaly Kuznetsov
> Cc: linux-scsi@xxxxxxxxxxxxxxx; Long Li; KY Srinivasan; Haiyang Zhang; James
> E.J. Bottomley; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] scsi: storvsc: make INQUIRY response SPC-compliant
> 
> On Wed, Jul 01, 2015 at 11:04:08AM +0200, Vitaly Kuznetsov wrote:
> > SPC-2/3/4 specs state that "The standard INQUIRY data (see table ...)
> > shall contain at least 36 bytes". Hyper-V host doesn't always honor this
> > requirement, e.g. when there is no physical device present at a particular
> > LUN host sets Peripheral qualifier to 011b and Additional length to 0
> > (thus making the reply 5-bytes long). Upper level SCSI stack complains
> > with 'INQUIRY result too short (5), using 36'. Fix the issue by mangling
> > Additional length field in host's reply at the driver level.
> 
> This looks like a big mess, and usage of phys_to_virt is not generally
> safe to start with.
> 
> If HyperV really is that broken the warning seems correct, but if you
> really have to get rid of it we could add a blist flag to not issue
> the warning in the core code instead of hacking around it in the driver.

Agreed. We have fixed this issue in win10 and I am trying to get the fix backported.

Regards,

K. Y
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