Re: [Xen-devel] [PATCH v4 2/4] docs: Introduce xenstore paths for PV driver information

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Ian Jackson [mailto:Ian.Jackson@xxxxxxxxxxxxx]
> Sent: 16 November 2015 17:56
> To: Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Ian Campbell; Jan Beulich; Keir (Xen.org);
> Tim (Xen.org)
> Subject: RE: [PATCH v4 2/4] docs: Introduce xenstore paths for PV driver
> information
> 
> Paul Durrant writes ("RE: [PATCH v4 2/4] docs: Introduce xenstore paths for
> PV driver information"):
> > " While xenstore and most tools and APIs are capable of dealing with
> > arbitrary binary data as values, this should generally be avoided.
> > Data should generally be human-readable for ease of management and
> > debugging; xenstore is not a high-performance facility and should be
> > used only for small amounts of control plane data.  Therefore xenstore
> > values should normally be 7-bit ASCII text strings containing bytes
> > 0x20..0x7f only, and should not contain a trailing nul byte.  (The
> > APIs used for accessing xenstore generally add a nul when reading, for
> > the caller's convenience.)"
> >
> > So, should we allow anything other than 7-bit ASCII?
> 
> It does say `generally'.  If this is user-facing, perhaps it should be
> UTF-8...

That sounds reasonable.

> 
> > > > +                  ATTRIBUTES -- Optional human readable text enclosed 
> > > > in
> > > > +                                parentheses to denote attributes of the
> > > > +                                software, e.g. "(debug)"
> > >
> > > What are the parentheses for ?  How might a toolstack provide
> > > facilities to match this ?
> >
> > I was not expecting any matching on attributes, since it's optional anyway. 
> > I
> guess the parentheses are indeed redundant.
> 
> Before you know it a user is going to want to say `reboot all my VMs
> with debugging PV drivers'...
> 

Ok, I'll point out that this is freeform text, the content and format is 
entirely up to the guest and therefore no meaning should be inferred.

  Paul

> Ian.

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