netdev - Re: New commands to configure IOV features

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Message-ID: <1348104190.4836.61.camel@deadeye.wl.decadent.org.uk>
Date:	Thu, 20 Sep 2012 02:23:10 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Greg Rose <gregory.v.rose@...el.com>,
	Yuval Mintz <yuvalmin@...adcom.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Ariel Elior <ariele@...adcom.com>,
	Eilon Greenstein <eilong@...adcom.com>,
	linux-pci <linux-pci@...r.kernel.org>
Subject: Re: New commands to configure IOV features

On Wed, 2012-09-19 at 17:19 -0700, Yinghai Lu wrote:
> On Wed, Sep 19, 2012 at 3:46 PM, Ben Hutchings
> <bhutchings@...arflare.com> wrote:
> > On Wed, 2012-09-19 at 15:17 -0700, Yinghai Lu wrote:
> >> +max_vfs_store(struct device *dev, struct device_attribute *attr,
> >> +                const char *buf, size_t count)
> >> +{
> >> +       unsigned long val;
> >> +       struct pci_dev *pdev = to_pci_dev(dev);
> >> +
> >> +       if (strict_strtoul(buf, 0, &val) < 0)
> >> +               return -EINVAL;
> >> +
> >> +       pdev->max_vfs = val;
> >> +
> >> +       return count;
> >> +}
> > [...]
> >
> > Then what would actually trigger creation of the VFs?  There's no way we
> > can assume that some sysfs attribute will be written before the PF
> > driver is loaded (what if it's built-in?).  I thought the idea was to
> > add a driver callback that would be called when the sysfs attribute was
> > written.
> 
> could just stop the device and add it back again?

This is highly disruptive and I think it would be totally unacceptable
for at least networking devices.

Ben.

> just like updated patch.
> 
> Thanks
> 
> Yinghai

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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