Re: [Qemu-devel] [PATCH 0/5] pc: make ROMs resizeable

[Michael S. Tsirkin]

On Wed, Nov 19, 2014 at 02:52:43PM +0100, Juan Quintela wrote:
> "Michael S. Tsirkin" <address@hidden> wrote:
> > On Wed, Nov 19, 2014 at 01:52:35PM +0530, Amit Shah wrote:
> >> On (Wed) 19 Nov 2014 [10:15:16], Michael S. Tsirkin wrote:
> >> > On Wed, Nov 19, 2014 at 01:01:14PM +0530, Amit Shah wrote:
> >> > > On (Mon) 17 Nov 2014 [22:08:46], Michael S. Tsirkin wrote:
> >> 
> >> > > > Note: migration stream is unaffected by these patches.
> >> > > > This makes it possible to enable this functionality
> >> > > > unconditionally, for all machine types.
> >> > > > 
> >> > > > In the future, this might be handy for other things,
> >> > > > such as changing kernels loaded on command line
> >> > > > across migrations.
> >> > > 
> >> > > I think that'll be too risky; unless we do S4 before / after
> >> > > migration to ensure the kernel realises things might be changing
> >> > > beneath its feet.
> >> > 
> >> > Well - guest never sees the resizing. It happens before we start the VM.
> >> > So I don't see the issue - could you clarify please?
> >> 
> >> Before we start the VM?  That's a really odd corner case (ie not worth
> >> bothering about?).  I took this to mean that the guest was running
> >> while migration happened.
> >> 
> >> 
> >>            Amit
> >
> > At the moment you get old ROM before reboot, new ROM after reboot.
> > Anyway, let's argue about this when someone proposes this.
> >
> > Guys, please drop responding to patch 0.  There's no code there.
> > Please review the actual code.
> 
> How can we answer: The code does what it tell it does, we are not happy
> with the whole idea?
> 
> Later, Juan.

My point is you seem to be unhappy with the general idea that ROMs
are migrated, because you think all ROMs should be bitwise
identical to what we shipped years ago, depending on machine type.

But that ship sailed in 1.7 I think.

If you want to revert that decision, start a new thread,
no need to respond to this patch.

All this patch does is remove the artificial "same size"
limitation, which - assuming we migrate ROMs with guests -
just makes sense.

-- 
MST