Re: [Qemu-devel] [RFC PATCH 0/5] modify boot order when vm is running

[Gonglei (Arei)]

> -----Original Message-----
> From: Michael S. Tsirkin [mailto:address@hidden
> Sent: Monday, July 07, 2014 9:08 PM
> To: Gonglei (Arei)
> Cc: address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> Huangweidong (C); Luonengjun; Huangpeng (Peter); chenliang (T)
> Subject: Re: [RFC PATCH 0/5] modify boot order when vm is running
> 
> On Mon, Jul 07, 2014 at 11:08:32AM +0000, Gonglei (Arei) wrote:
> > > -----Original Message-----
> > > From: Michael S. Tsirkin [mailto:address@hidden
> > > Sent: Monday, July 07, 2014 5:29 PM
> > > To: Gonglei (Arei)
> > > Cc: address@hidden; address@hidden; address@hidden;
> > > address@hidden; address@hidden; address@hidden;
> > > address@hidden; address@hidden; address@hidden;
> > > address@hidden; address@hidden; address@hidden;
> > > address@hidden; address@hidden; address@hidden;
> > > address@hidden; address@hidden; address@hidden;
> > > address@hidden; address@hidden; address@hidden;
> > > Huangweidong (C); Luonengjun; Huangpeng (Peter); chenliang (T)
> > > Subject: Re: [RFC PATCH 0/5] modify boot order when vm is running
> > >
> > > On Mon, Jul 07, 2014 at 05:10:56PM +0800, address@hidden
> wrote:
> > > > From: Chenliang <address@hidden>
> > > >
> > > > Sometime, we want to modify boot order of vm without shutdown it.
> > > > This sets of patches add one qmp to achieve it. And fix some little
> > > > bug when device is hotpluged.
> > > >
> > > > Chenliang (5):
> > > >   bootindex: add *_boot_device_path function
> > > >   bootindex: reset bootindex when vm reset
> > > >   bootindex: delete boot index when device is removed
> > > >   bootindex: add qmp to set boot index when vm is running
> > > >   bootindex: fix memory leak when ppc sets boot index
> > >
> > > Unfortunately at least for PC, boot order is exposed
> > > in fw cfg which can not change while guest is running.
> >
> > Yes, so we should assure it take effect after the guest rebooting.
> 
> Does this patch do it like this?

Yes.

> I didn't get it. How is this handled?

By change the order of global fw_boot_order, when the guest rebooting,
Seabios will read the fw_cfg file again. 

[RFC PATCH 1/5] bootindex: add *_boot_device_path function

do this work.

> Maybe more code comments would be helpful to make this
> clear to readers.
> 

OK.

We will add more comments for non RFC patchsets 
after QEMU 2.1 "hard freeze ".

Thanks.

Best regards,
-Gonglei

> > > I suspect we need to change how we report boot order to guests.
> > > While we are at it, maybe we can fix the silly bootindex
> > > convention: I think people really want to specify boot *order*,
> > > not boot index.
> > >
> > Agreed.
> >
> > But at present, the boot index can be used for the boot order
> > except "-boot" command line. Because "-boot" only can assign
> > the guest booting from HD or Network or Floppy etc.. but cannot
> > assign the index of hard disks or PXE net cards, which not be enough
> > for many scenes, such as P2V, or two different system hard disks
> > (vda/sda/hda).
> >
> >
> > Best regards,
> > -Gonglei