From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bastian Blank Subject: Re: [PATCH 4 of 4] Linux pvops: xen pci platform device driver Date: Wed, 3 Mar 2010 17:14:28 +0100 Message-ID: <20100303161428.GB26656@wavehammer.waldi.eu.org> References: <20100303121726.GA26656@wavehammer.waldi.eu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Stefano Stabellini Cc: "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" List-Id: xen-devel@lists.xenproject.org On Wed, Mar 03, 2010 at 03:52:07PM +0000, Stefano Stabellini wrote: > On Wed, 3 Mar 2010, Bastian Blank wrote: > > Why is version 1 grant table the default on HVM? > Because version 2 is known not to work on HVM, fixing this is on my TODO > list. Well, then the later modification to 2 in the hvm case is bogus. > > > +/* NB. [aux-]ide-disks options do not unplug IDE CD-ROM drives. */ > > > +/* NB. aux-ide-disks is equiv to ide-disks except ignores primary master. */ > > > +static char *dev_unplug; > > > +module_param(dev_unplug, charp, 0644); > > > +MODULE_PARM_DESC(dev_unplug, "Emulated devices to unplug: " > > > + "[all,][ide-disks,][aux-ide-disks,][nics]\n"); > > > > What is this parameter about? > > During the initialization of the xen pci device driver, we write to a > magic ioport that causes qemu to unplug some emulated devices, disc and > network in particular. > This parameter is meant to present the user a choice about what emulated > devices to unplug. Somehow I don't think this belongs here. It looks like a workaround, you can always ask qemu to not bind them at the beginning and the guest system to not provide drivers. > > > +#define XEN_IOPORT_BASE 0x10 > > > > Why are this constants defined in the driver themself? They only make > > sense if there are two components making use of them. > Yep, the other one is qemu. Well, if it is a published interface move it into a header file. > > > + if (request_mem_region(mmio_addr, mmio_len, DRV_NAME) == NULL) { > > > + printk(KERN_ERR ":MEM I/O resource 0x%lx @ 0x%lx busy\n", > > > + mmio_addr, mmio_len); > > > + return -EBUSY; > > > > Why is this a sign of busy? > > I think we were just trying to follow the behaviour of the other drivers > of real pci devices. > I am not sure how this condition could happen on Xen. I checked again. There are many different return values used, but EBUSY seems to be the most. Bastian -- The heart is not a logical organ. -- Dr. Janet Wallace, "The Deadly Years", stardate 3479.4