Re: [Qemu-devel] [PATCH 03/10] S390: Check Bootdevice Type

[Dominik Dingel]

On Fri, 26 Apr 2013 18:05:02 +0200
Alexander Graf <address@hidden> wrote:

> 
> On 26.04.2013, at 18:01, Christian Borntraeger wrote:
> 
> > On 26/04/13 17:48, Alexander Graf wrote:
> > 
> >>> So I suggest to go with this patch and implement later on what we
> >>> agree upon?
> >> 
> >> I don't see how having "first device we find" is any better than a 
> >> rushed interface we need to agree on right before 1.5 hard freeze. 
> > 
> > Exactly, find first device isnt better ;-)
> > See, the current code chooses the first subchannel that matches. This
> > boils down to "a random disk" as soon as you have more than one.
> > 
> > With this patch the user can at least specify the devno of the disk.It
> > even works out of the box with libvirt.
> > 
> > Let's just release 1.5 with the very simple one and then go for something 
> > awesome in the next version.
> > 
> > Exactly - and having a list is more in the awesome area. Beiing able to
> > specify the first disk and pass that in a register to the bios is of
> > course not a full-features interface, but it works and can be changed.
> 
> My main concern is backwards compatibility. If we introduce a command line 
> interface now, we have to support it forever. I'd rather only support one 
> interface, rather than 2 out of which one is only legacy for 1.5 
> compatibility.

We only enable, don't introduce the existing command line interface for 
bootindex. The loadparm thing is already kind of list, as the loadparm is 
stored with every device. 
But as I wrote in the cover letter, we also could just for the start only 
implement the bootindex.  

> 
> > Just to double check: do you agree that we can change the interface between
> > ipl device and bios at any time?
> 
> I think that's a fair thing to do, though I wouldn't encourage it.
> 
> 
> Alex
> 

Dominik