Re: [Qemu-devel] [PATCH 1/6] bootindex: add {del, modify}_boot_device_path function

[Gonglei (Arei)]

> -----Original Message-----
> From: Gerd Hoffmann [mailto:address@hidden
> Sent: Thursday, July 24, 2014 9:25 PM
> Subject: Re: [PATCH 1/6] bootindex: add {del,modify}_boot_device_path
> function
> 
>   Hi,
> 
> > > Hmm.  I think we should simply lookup the device and modify the
> > > bootindex, leaving the entry as-is otherwise.  In case the new bootindex
> > > is already used by another device just throw an error.
> > >
> > If we just throw an error but not change the bootindex is already used,
> > we cannot achieve our purpose. For example, we configure a hard disk,
> > which bootindex=1, a nic which bootindex=2. If we want to boot the guest
> > from nic firstly, we should must set the nic's bootindex to 1. AFAICT, the
> > bootindex=1 always be used.
> 
> No.  The devices are simply sorted by bootindex.  You don't have to use
> '1'.  And you can have holes in your numbering and use --for example --
> 3+5.
> 
Yes, you are right. I make a mistake because libvirt will default assign the 
first 
disk as bootindex=1.

> So you can start qemu with hd=2,cdrom=3,nic=4, then set nic=1 or cdrom=1
> for a guest install, change it back when done.
>
Yes.
 
> > > Should be del_boot_device_path(DeviceState *dev) and simply delete all
> > > entries belonging to the device.  Patch #3 can be much simpler then as
> > > we can call the function from generic device cleanup code.
> > >
> > Because the IDE device may configure two kind of disk, HD and CDROM, we
> > have to distinguish them by suffix.
> 
> Yes, the suffix indicated whenever the device is a disk or cdrom.  But
> you'll never have both cdrom+disk paths attached to a single device.
> Therefore the device is enough to identify the bootpath entry, you don't
> need the suffix for that.
> 
Agreed. Thank you so much, Gerd. 
A new version will be posted later.

Best regards,
-Gonglei