On Sat, 30 Jun 2007 12:42:06 -0400 Jeff Garzik <[EMAIL PROTECTED]> wrote:
> Arjan van de Ven wrote: > > Matthew Garrett wrote: > >> Do you still get link beat detection when the phy is powered down? > > > does that matter? > > If the interface is down, nic drivers aren't expected to detect link... > > if userspace wants to find link status it should have the interface up. > > > Definitely matters. Switch renegotiation can take a while, and you must > take into account the common case of interface bouncing (immediate down, > then up). > > Hoards actively complained the few times we experimented with this, > because of e.g. DHCP's habit of bouncing the interface, which resulted > in PHY power bouncing, which resulted in negotiation, which resulted in > an excrutiating wait on various broken or stupid switches. > > Overall, this may be classed with other problems of a similar sort: we > can power down a PHY, but that removes hotplug capability and extends > partner/link negotiation time. > > Like SATA, we actually want to support BOTH -- active hotplug and PHY > power-down -- and so this wanders into power management policy. > > Give me a knob, and we can program plenty of ethernet|SATA|USB|... > drivers to power down the PHY and save power. > > Jeff We do have IFF_DORMANT, but almost no driver uses it. And most certainly, the common applications wouldn't know how to use it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
