Re: [Qemu-devel] [RFC] qemu-ga: Introduce guest-hibernate command

[Luiz Capitulino]

On Thu, 08 Dec 2011 19:14:43 -0600
Michael Roth <address@hidden> wrote:

> On 12/08/2011 12:52 PM, Luiz Capitulino wrote:
> > This is basically suspend to disk on a Linux guest.
> 
> Nice!
> 
> >
> > Signed-off-by: Luiz Capitulino<address@hidden>
> > ---
> >
> > This is an RFC because I did it as simple as possible and I'm open to
> > suggestions...
> >
> > Now, while testing this or even "echo disk>  /sys/power/state" I get several
> > funny results. Some times qemu just dies after printing that message:
> >
> >   "Guest moved used index from 20151 to 1"
> >
> > Some times it doesn't die, but I'm unable to log into the guest: I type
> > username&  password but the terminal kind of locks (the shell doesn't run).
> 
> Triggered this pretty easily on FC15 amd64:
> 
> qemu-system-x86_64: Guest moved used index from 13024 to 80
> 
> I'll see if I can get a trace of what's happening on my end.
> 
> >
> > Some times it works...
> >
> >   qapi-schema-guest.json     |   11 +++++++++++
> >   qga/guest-agent-commands.c |   19 +++++++++++++++++++
> >   2 files changed, 30 insertions(+), 0 deletions(-)
> >
> > diff --git a/qapi-schema-guest.json b/qapi-schema-guest.json
> > index fde5971..2c5bbcf 100644
> > --- a/qapi-schema-guest.json
> > +++ b/qapi-schema-guest.json
> > @@ -215,3 +215,14 @@
> >   ##
> >   { 'command': 'guest-fsfreeze-thaw',
> >     'returns': 'int' }
> > +
> > +##
> > +# @guest-hibernate
> > +#
> > +# Save RAM contents to disk and powerdown the guest.
> > +#
> > +# Notes: This command doesn't return on success.
> > +#
> > +# Since: 1.1
> > +##
> > +{ 'command': 'guest-hibernate' }
> > diff --git a/qga/guest-agent-commands.c b/qga/guest-agent-commands.c
> > index 6da9904..9dd4060 100644
> > --- a/qga/guest-agent-commands.c
> > +++ b/qga/guest-agent-commands.c
> > @@ -550,6 +550,25 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
> >   }
> >   #endif
> >
> > +#define LINUX_SYS_STATE_FILE "/sys/power/state"
> > +
> > +void qmp_guest_hibernate(Error **err)
> > +{
> > +    int fd;
> > +
> > +    fd = open(LINUX_SYS_STATE_FILE, O_WRONLY);
> > +    if (fd<  0) {
> > +        error_set(err, QERR_OPEN_FILE_FAILED, LINUX_SYS_STATE_FILE);
> > +        return;
> > +    }
> > +
> > +    if (write(fd, "disk", 4)<  0) {
> > +        error_set(err, QERR_UNDEFINED_ERROR);
> > +    }
> 
> There's basically no chance of this returning, so we should issue it 
> asynchronously like we do with qmp_guest_shutdown(). Also agreed on 
> Daniel's point that we should use pm-hibernate, but failing back to this 
> should be okay...assuming the virtio issue isn't indicative of some 
> fundamental problem with that approach...

Ok, I'll make these changes and submit v2.

> 
> > +
> > +    close(fd);
> > +}
> > +
> >   /* register init/cleanup routines for stateful command groups */
> >   void ga_command_state_init(GAState *s, GACommandState *cs)
> >   {
>