[virtio-comment] Re: [PATCH v5 4/5] shared memory: Define PCI capability

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Cornelia Huck (cohuck@redhat.com) wrote:
> On Thu, 27 Jun 2019 20:28:29 +0100
> "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> 
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Define the PCI capability used for enumerating shared memory regions.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  content.tex | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> > 
> > diff --git a/content.tex b/content.tex
> > index 63e9179..fcf0d81 100644
> > --- a/content.tex
> > +++ b/content.tex
> > @@ -689,6 +689,8 @@ \subsection{Virtio Structure PCI Capabilities}\label{sec:Virtio Transport Option
> >  #define VIRTIO_PCI_CAP_DEVICE_CFG        4
> >  /* PCI configuration access */
> >  #define VIRTIO_PCI_CAP_PCI_CFG           5
> > +/* Shared memory region */
> > +#define VIRTIO_PCI_CAP_SHARED_MEMORY_CFG 8
> >  \end{lstlisting}
> >  
> >          Any other value is reserved for future use.
> > @@ -1075,6 +1077,24 @@ \subsubsection{Device-specific configuration}\label{sec:Virtio Transport Options
> >  
> >  The \field{offset} for the device-specific configuration MUST be 4-byte aligned.
> >  
> > +\subsubsection{Shared memory capability}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Shared memory capability}
> > +
> > +Shared memory regions \ref{sec:Basic Facilities of a Virtio
> > +Device / Shared Memory Regions} are enumerated on the PCI transport
> > +as a sequence of VIRTIO_PCI_CAP_SHARED_MEMORY_CFG capabilities, one per region.
> > +
> > +The capability is defined by a struct virtio_pci_cap64 and
> > +utilises the \field{cap.id} to allow multiple shared memory
> > +regions per device.
> 
> Maybe add a sentence here
> 
> "The identifier in \field{cap.id} does not denote a certain order of
> preference; it is only used to uniquely identify a region."
> 
> (as per discussion of patch 2)

Added.

> > +
> > +\devicenormative{\paragraph}{Device-specific configuration}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Shared memory capability}
> > +
> > +The region defined by the combination of the \field {cap.offset},
> > +\field {cap.offset_hi}, and \field {cap.length}, \field
> > +{cap.length_hi} fields MUST be contained within the declared bar.
> > +
> > +The \field{cap.id} MUST be unique for any one device instance.
> > +
> >  \subsubsection{PCI configuration access capability}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability}
> >  
> >  The VIRTIO_PCI_CAP_PCI_CFG capability
> 
> Else, looks good to me.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

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