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Re: [Qemu-devel] [Xen-devel] [PATCH 2/2] xenfb: Add comment documentatio
From: |
Owen Smith |
Subject: |
Re: [Qemu-devel] [Xen-devel] [PATCH 2/2] xenfb: Add comment documentation |
Date: |
Fri, 26 Sep 2014 10:20:25 +0000 |
> -----Original Message-----
> From: David Vrabel
> Sent: 22 September 2014 11:16
> To: Owen Smith; address@hidden
> Cc: Stefano Stabellini; address@hidden; Ian Campbell
> Subject: Re: [Xen-devel] [PATCH 2/2] xenfb: Add comment documentation
>
> On 22/09/14 10:04, Owen smith wrote:
> > Add documentation for page-ref, page-gref and event-channel.
> >
> > Signed-off-by: Owen smith <address@hidden>
> > ---
> > xen/include/public/io/fbif.h | 25 +++++++++++++++++++++++++
> > 1 file changed, 25 insertions(+)
> >
> > diff --git a/xen/include/public/io/fbif.h
> > b/xen/include/public/io/fbif.h index cc25aab..ba3f524 100644
> > --- a/xen/include/public/io/fbif.h
> > +++ b/xen/include/public/io/fbif.h
> > @@ -26,6 +26,31 @@
> > #ifndef __XEN_PUBLIC_IO_FBIF_H__
> > #define __XEN_PUBLIC_IO_FBIF_H__
> >
> > +/*
> > + * Frontend XenStore Nodes
> > + * -----------------------
> > + *
> > + * page-ref
> > + * Values: <uint64_t>
> > + * Optional, "page-gref" is used if "page-ref" is not set.
> > + *
> > + * The MFN of a page of memory for the shared ring structures. If not
> > + * present, "page-gref" must be set.page-ref" overrides "page-gref".
>
> I think you mean GFN here, not MFN.
GFN would be more correct.
>
> > + * page-gref
> > + * Values: <uint32_t>
> > + * Only required if "page-ref" is NOT set.
> > + *
> > + * A grant reference to the memory page to be mapped for the shared
> ring
> > + * structures. Must be present if "page-ref" is not present.
>
> Should there be some negotiation for which of page-ref or page-gref is
> required/preferred by the backend?
>
> The same applies to kbdif as well.
>
I've not added negotiation, as I wanted minimum changes when "page-ref" is
specified.
With the kbdif device only, not investigated the vfb, a backend only supporting
"page-gref"
will break a lot of frontends (I saw breaks in Ubuntu, which advertises both if
I forced page-gref)
> David