Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-10 Thread Dr. David Alan Gilbert
* Liran Alon (liran.a...@oracle.com) wrote: > > > On 6 Jun 2019, at 16:31, Dr. David Alan Gilbert wrote: > > > >>> > >>> So we still need to tie subsections to machine types; that way > >>> you don't send them to old qemu's and there for you don't have the > >>> problem of the qemu receiving

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Liran Alon
> On 6 Jun 2019, at 16:31, Dr. David Alan Gilbert wrote: > >>> >>> So we still need to tie subsections to machine types; that way >>> you don't send them to old qemu's and there for you don't have the >>> problem of the qemu receiving something it doesn't know. >> >> I agree that if there is

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Dr. David Alan Gilbert
* Liran Alon (liran.a...@oracle.com) wrote: > > > > On 6 Jun 2019, at 14:07, Dr. David Alan Gilbert wrote: > > It's tricky; for distro-based users, hitting 'update' and getting both > > makes a lot of sense; but as you say you ened to let them do stuff > > individually if they want to, so

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Roman Kagan
On Thu, Jun 06, 2019 at 01:09:56PM +0300, Liran Alon wrote: > First, machine-type express the set of vHW behaviour and properties that is > exposed to guest. > Therefore, machine-type shouldn’t change for a given guest lifetime > (including Live-Migrations). > Otherwise, guest will experience

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Liran Alon
> On 6 Jun 2019, at 14:07, Dr. David Alan Gilbert wrote: > > * Liran Alon (liran.a...@oracle.com) wrote: >> >> >>> On 6 Jun 2019, at 13:39, Dr. David Alan Gilbert wrote: >>> >>> * Liran Alon (liran.a...@oracle.com) wrote: > On 6 Jun 2019, at 12:23, Dr. David Alan Gilbert

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Dr. David Alan Gilbert
* Liran Alon (liran.a...@oracle.com) wrote: > > > > On 6 Jun 2019, at 13:39, Dr. David Alan Gilbert wrote: > > > > * Liran Alon (liran.a...@oracle.com) wrote: > >> > >> > >>> On 6 Jun 2019, at 12:23, Dr. David Alan Gilbert > >>> wrote: > >>> > >>> * Liran Alon (liran.a...@oracle.com)

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Liran Alon
> On 6 Jun 2019, at 13:39, Dr. David Alan Gilbert wrote: > > * Liran Alon (liran.a...@oracle.com) wrote: >> >> >>> On 6 Jun 2019, at 12:23, Dr. David Alan Gilbert wrote: >>> >>> * Liran Alon (liran.a...@oracle.com) wrote: > On 6 Jun 2019, at 11:42, Dr. David Alan Gilbert

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Dr. David Alan Gilbert
* Liran Alon (liran.a...@oracle.com) wrote: > > > > On 6 Jun 2019, at 12:23, Dr. David Alan Gilbert wrote: > > > > * Liran Alon (liran.a...@oracle.com) wrote: > >> > >> > >>> On 6 Jun 2019, at 11:42, Dr. David Alan Gilbert > >>> wrote: > >>> > >>> * Liran Alon (liran.a...@oracle.com)

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Liran Alon
> On 6 Jun 2019, at 12:23, Dr. David Alan Gilbert wrote: > > * Liran Alon (liran.a...@oracle.com) wrote: >> >> >>> On 6 Jun 2019, at 11:42, Dr. David Alan Gilbert wrote: >>> >>> * Liran Alon (liran.a...@oracle.com) wrote: Hi, Looking at QEMU source code, I am puzzled

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Dr. David Alan Gilbert
* Liran Alon (liran.a...@oracle.com) wrote: > > > > On 6 Jun 2019, at 11:42, Dr. David Alan Gilbert wrote: > > > > * Liran Alon (liran.a...@oracle.com) wrote: > >> Hi, > >> > >> Looking at QEMU source code, I am puzzled regarding how migration > >> backwards compatibility is preserved

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Liran Alon
> On 6 Jun 2019, at 11:42, Dr. David Alan Gilbert wrote: > > * Liran Alon (liran.a...@oracle.com) wrote: >> Hi, >> >> Looking at QEMU source code, I am puzzled regarding how migration backwards >> compatibility is preserved regarding X86CPU. >> >> As I understand it, fields that are based

Re: [Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-06 Thread Dr. David Alan Gilbert
* Liran Alon (liran.a...@oracle.com) wrote: > Hi, > > Looking at QEMU source code, I am puzzled regarding how migration backwards > compatibility is preserved regarding X86CPU. > > As I understand it, fields that are based on KVM capabilities and guest > runtime usage are defined in VMState

[Qemu-devel] QEMU/KVM migration backwards compatibility broken?

2019-06-05 Thread Liran Alon
Hi, Looking at QEMU source code, I am puzzled regarding how migration backwards compatibility is preserved regarding X86CPU. As I understand it, fields that are based on KVM capabilities and guest runtime usage are defined in VMState subsections in order to not send them if not necessary.