Re: [Xen-devel] [RFC PATCH V3 12/16] netback: multi-page ring support

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, 2012-01-30 at 16:35 +0000, Jan Beulich wrote:
> >>> On 30.01.12 at 15:45, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> > -int xenvif_map_frontend_rings(struct xenvif *vif,
> > -			      grant_ref_t tx_ring_ref,
> > -			      grant_ref_t rx_ring_ref)
> > +int xenvif_map_frontend_rings(struct xen_comms *comms,
> > +			      int domid,
> > +			      unsigned long ring_ref[],
> > +			      unsigned int  ring_ref_count)
> >  {
> > -	void *addr;
> > -	struct xen_netif_tx_sring *txs;
> > -	struct xen_netif_rx_sring *rxs;
> > -
> > -	int err = -ENOMEM;
> > +	struct gnttab_map_grant_ref op[NETBK_MAX_RING_PAGES];
> > +	unsigned int i;
> > +	int err = 0;
> >  
> > -	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
> > -				     tx_ring_ref, &addr);
> 
> Any reason why you don't just extend this function (in a prerequisite
> patch) rather than open coding a common utility function (twice) here,
> so that other backends (blkback!) can benefit later as well.
> 
> Jan
> 

I'm mainly focusing on netback stuffs, so the code is slightly coupled
with netback -- NETBK_MAX_RING_PAGES.

To extend xenbus_map_ring_valloc and make more generic, it requires
setting a global maximum page number limits on rings, I think it will
require further investigation and code refactor -- which I have no time
to attend to at the moment. :-/


Wei.



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