Re: [Qemu-devel] [PATCH v5 24/24] slirp: fix ipv6 timers

[Samuel Thibault]

Pavel Dovgalyuk, le jeu. 26 juil. 2018 10:08:29 +0300, a ecrit:
> virtual clock should be used by the virtual devices.
> slirp module is not the virtual device. Therefore processed packets
> become visible to the guest after passing to the virtual network card.
> Before that it can create any timers that should not change the state of the 
> guest.

I'm not sure I understand that part correctly. slirp is not a "device"
strictly speaking, but it has a whole foot in the virtual world. All
TCP/UDP/ARP/RA timings are related to the guest timing, so

> > > this service is not related to the guest state.

seems incorrect. At the moment the ip6_icmp timer's current value is not
saved in the guest state, but in principle it should, so that the guest
does see the RAs at a regular rate. In practice we don't care because
the timing is randomized anyway.

> intended to be used for the internal QEMU purposes, but stops when VM
> is stopped.

I again don't understand this. The ip6_icmp timing is not for internal
QEMU purpose, its whole point is how often RAs are sent to the guest.

slirp's guest part is not a device as directly seen by guest I/O, but
it's a router device as seen through guest packets. Think of it like a
USB device, which is seen by the guest through USB packets.

Samuel