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

[Samuel Thibault]

Pavel Dovgalyuk, le jeu. 26 juil. 2018 10:37:03 +0300, a ecrit:
> > From: Samuel Thibault [mailto:address@hidden
> > Pavel Dovgalyuk, le jeu. 26 juil. 2018 10:08:29 +0300, a ecrit:
> > > > As documented:
> > > >
> > > >  * @QEMU_CLOCK_REALTIME: Real time clock
> > > >  *
> > > >  * The real time clock should be used only for stuff which does not
> > > >  * change the virtual machine state, as it runs even if the virtual
> > > >  * machine is stopped.
> > > >
> > > > There is no reason to "send RAs" while the machine is stopped.
> > >
> > > I see.
> > > Then we'll need one more clock. Which works like realtime+virtual:
> > > intended to be used for the internal QEMU purposes, but stops when
> > > VM is stopped.
> > 
> > Just to be sure: what is meant by "is stopped"? Is it a pause (thus time
> > does not advance within the guest), or is it just sleeping because it
> > has nothing to do?
> 
> Paused with HMP/QMP command.
> As virtual clock runs only if VM is not paused.

Then all other uses of qemu_clock in slirp are bogus and need to be
fixed like ip6_icmp: they are using QEMU_CLOCK_REALTIME, but they want
it not to progress while the guest time is not advancing. Otherwise on
guest resume after a long pause basically all TCP/UDP/ARP timings will
have expired.

Samuel