From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel De Graaf Subject: Re: [PATCH 2/7] xen-gntdev: Change page limit to be global instead of per-open Date: Tue, 11 Jan 2011 13:18:09 -0500 Message-ID: <4D2C9EE1.4010705@tycho.nsa.gov> References: <1292545063-32107-1-git-send-email-dgdegra@tycho.nsa.gov> <1292545063-32107-3-git-send-email-dgdegra@tycho.nsa.gov> <20110110215245.GD15016@dumpdata.com> <4D2C50EE.8010200@tycho.nsa.gov> <20110111175146.GG14017@dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110111175146.GG14017@dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Konrad Rzeszutek Wilk Cc: jeremy@goop.org, xen-devel@lists.xensource.com, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On 01/11/2011 12:51 PM, Konrad Rzeszutek Wilk wrote: > 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? > No, because the semantics of what the limit is covering have changed. The new limit is per-domain, and if there was any existing code that set the limit, it would have been a per-open value and probably too low. I think it was suggested that the call be removed from the Xen API; I can submit a patch to do that, if you want. The new value is probably best set in modprobe.conf if gntdev is a module; the sysfs interface is useful for runtime adjustment or if it is builtin. -- Daniel De Graaf National Security Agency