From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 2/7] xen-gntdev: Change page limit to be
	global instead of per-open
Date: Tue, 11 Jan 2011 12:51:46 -0500
Message-ID: <20110111175146.GG14017@dumpdata.com>
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To: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: jeremy@goop.org, xen-devel@lists.xensource.com, Ian.Campbell@citrix.com
List-Id: xen-devel@lists.xenproject.org

On Tue, Jan 11, 2011 at 07:45:34AM -0500, Daniel De Graaf wrote:
> On 01/10/2011 04:52 PM, Konrad Rzeszutek Wilk wrote:
> >>  static long gntdev_ioctl(struct file *flip,
> >>  			 unsigned int cmd, unsigned long arg)
> >>  {
> >> @@ -555,9 +538,6 @@ static long gntdev_ioctl(struct file *flip,
> >>  	case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
> >>  		return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
> >>  
> >> -	case IOCTL_GNTDEV_SET_MAX_GRANTS:
> >> -		return gntdev_ioctl_set_max_grants(priv, ptr);
> > 
> > Would it make sense to return -EPNOTSUPPORTED? Or does it not really
> > matter as nobody has been using this ioctl call?
> 
> Does this produce a clearer error message than the default -ENOIOCTLCMD?
> It's possible that some people use it, since it was exposed as an API.

Looking at the Xen tools the user of this is:
xc_gnttab_set_max_grants which would end up returning whatever the
error is. I don't see any users of this in the Xen tools, thought there might
be some in the XCP code. Lets stay with your ENOIOCTLCMD.

However, I was wondering if you are going to submit a patch to the Xen
tool stack so that it can utlize the SysFS interface to set the limits
for that API call?