On 05/02/2013 12:59, Thor Lancelot Simon wrote:
On Tue, Feb 05, 2013 at 12:02:12PM +0000, Roy Marples wrote:However, some drivers incorrectly reset PHY on a MTU change which triggers the link down/up and kind of gets into a little loop.Some drivers _have to_ reset the PHY on an MTU change. Admittedly,a lot less than used to be the case, but on some hardware, it is stillunavoidable.
Really? I was under the impression MTU was purely a software thing. But then I'm no driver expert.
Is there anyway of knowing this from userland?I mean if we can find out then we could turn off carrier detection on that interface for a small timeframe to give the driver enough time to come back. I don't want to do this by default because it's not desired behavior - we have no way of distinguishing the carrier dropping from the MTU changing.
If the MTU is being "changed" to the default, can't dhcpcd leave it alone? Or is that already the case, and on this network, can we thus assume the MTU is not 1500?
The problem here is when the link is lost, dhcpcd restores the MTU to the prior value.
Thanks Roy