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Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resiz
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize |
Date: |
Wed, 19 Nov 2014 14:44:32 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 19/11/2014 14:28, Michael S. Tsirkin wrote:
> >
> > qemu-2.0 -M pc-2.0 -> qemu-2.2 -M pc-2.0
> >
> > what BIOS should the second qemu use? the one that existed on qemu-2.0
> > time or the one that existed on qemu-2.2 time? You can allow for
> > bugfixes, but not for big changes like moving where the acpi tables were
> > generated, etc, etc.
>
> > I really think that we should use the BIOS from qemu-2.0 era. And my
> > understanding is that you defend that we should use the qemu-2.2 era
> > BIOS.
>
> Not only that. We already do. And we don't intend to change that for 2.2.
Am I missing a part of the discussion? When we migrate, the second QEMU
uses the BIOS from the first.
So:
qemu-2.0 -M pc-2.0 -> qemu-2.2 -M pc-2.0
uses 2.0 BIOS
qemu-2.2 -M pc-2.0 -> qemu-2.0 -M pc-2.0
uses 2.2 BIOS
Both should work, in general. BIOS is rarely the reason for
incompatibilities. However, breakage can happen, for example I know
that RHEL7 SeaBIOS does not work on RHEL6. RHEL6 SeaBIOS works on
RHEL7, but it needs a couple workarounds.
Shipping a separate BIOS for different machine types is unrealistic and
pointless. It would also be a good terrain for bug reports, unless you
also do things like "forbid creating -device megasas-gen2 on 2.1 because
it was introduced in 2.2". Remember that libvirt keeps the same machine
type for the whole life of a virtual machine definition, even if other
parts of the hardware (e.g. disks or NICs) change.
Paolo
- [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, (continued)
- [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/17
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/17
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Paolo Bonzini, 2014/11/18
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/18
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Juan Quintela, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Juan Quintela, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Juan Quintela, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Juan Quintela, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Dr. David Alan Gilbert, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Paolo Bonzini, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Dr. David Alan Gilbert, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Paolo Bonzini, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Dr. David Alan Gilbert, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Michael S. Tsirkin, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Dr. David Alan Gilbert, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Juan Quintela, 2014/11/19
- Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize, Paolo Bonzini, 2014/11/19