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

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jul 07, 2014 at 11:08:32AM +0000, Gonglei (Arei) wrote:
> > -----Original Message-----
> > From: Michael S. Tsirkin [mailto:mst@redhat.com]
> > Sent: Monday, July 07, 2014 5:29 PM
> > To: Gonglei (Arei)
> > Cc: qemu-devel@nongnu.org; afaerber@suse.de; agraf@suse.de;
> > stefanha@redhat.com; akong@redhat.com; aik@ozlabs.ru;
> > alex.williamson@redhat.com; armbru@redhat.com; eblake@redhat.com;
> > kwolf@redhat.com; peter.maydell@linaro.org; lcapitulino@redhat.com;
> > pbonzini@redhat.com; lersek@redhat.com; kraxel@redhat.com;
> > imammedo@redhat.com; dmitry@daynix.com; marcel.a@redhat.com;
> > peter.crosthwaite@xilinx.com; rth@twiddle.net; somlo@cmu.edu;
> > 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, arei.gonglei@huawei.com wrote:
> > > From: Chenliang <chenliang88@huawei.com>
> > >
> > > 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?
I didn't get it. How is this handled?
Maybe more code comments would be helpful to make this
clear to readers.

> > 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