[PATCH v7 0/5] um: suspend/resume support

[Johannes Berg]

On Thu, 2020-12-03 at 10:06 +0000, Anton Ivanov wrote:
> 
> Works nicely and I will ACK them shortly.

:)

> I will see if I can add some WOL functionality to the vector drivers.

That might be nice.

> It is definitely possible for the ones which use a raw socket - you
> leave them as capable of generating a SIGIO, but load a "sleeptime"
> BPF filter which allows only the types of packets that are entitled to
> wake you up - WOL magic, ARP, unicast to your own MAC, etc. IIRC
> ethtool has a list of all the possible options. When you wake up, you
> swap back the old filter (if there was any).

Right, you can set the IRQ to allow wakeup using just the normal
irq_set_irq_wake() function, and then you get woken up on anything.

And with a BPF filter you can drop all the other packets, so you don't
get a full socket queue either (in the host) that would prevent
something from working.

Indeed there are more options than I thought there were:

           wol p|u|m|b|a|g|s|f|d...
                  Sets Wake-on-LAN options.  Not all devices support this.  The argument to this option is a string
                  of characters specifying which options to enable.

                  p   Wake on PHY activity
                  u   Wake on unicast messages
                  m   Wake on multicast messages
                  b   Wake on broadcast messages
                  a   Wake on ARP
                  g   Wake on MagicPacket™
                  s   Enable SecureOn™ password for MagicPacket™
                  f   Wake on filter(s)
                  d   Disable  (wake  on  nothing).  This option
                      clears all previous options.


p would be trivial, requiring only a call to irq_set_irq_wake(), u, m,
b, a, g and s would require BPF filters, and f (filter) is difficult,
you'd need to support RX-flow-spec stuff, apparently.


I'm trying to add support for virtio ... hmm. Actually p or u might be
very useful there for me, but it'd require changing the virtio-net spec
I guess ... Maybe I'll just do an out-of-band wake device for my system
:)

johannes