Re: [Qemu-devel] [PATCH RFC] hw/pc: set q35 as the default x86 machine

[Igor Mammedov]

On Mon, 4 Jun 2018 04:38:22 +0300
"Michael S. Tsirkin" <address@hidden> wrote:

> On Sun, Jun 03, 2018 at 12:27:49PM +0300, Marcel Apfelbaum wrote:
> > Moving to QEMU 3.0 seems like a good opportunity for such a change.
> > 
> > I440FX is really old and does not support modern features like IOMMU.
> > Q35's SATA emulation is faster than pc's IDE, native PCI express hotplug
> > is cleaner than ACPI based one and so on...
> > 
> > Also the libvirt guys added very good support for the Q35 machine (thanks!).
> > 
> > Management software should always specify the machine type and for the
> > current setups, adding '-machine pc' to the command line is not such a
> > big deal.
> > 
> > In time the pc machine will fade out and we will probably stop adding
> > new versions at some point.
> > 
> > Signed-off-by: Marcel Apfelbaum <address@hidden>  
> 
> For command line users, I think changing the default isn't nice.
> 
> Yes it's easy to add -machine pc but there's no documentation
> that tells you to do so. Add to that shortcuts like -cdrom
> stop working, hotplug needs extra bridges to work, and one
> can see that while management tool users benefit from q35,
> command line users will suffer.
Maybe we should mark 'pc' default as deprecated first,
like we do with CLI options that we wish to drop in future?

That way we 'create' documentation, so users would be aware
of the change and have time to fix their CLI if they prefer
'pc' machine.


> Can't we add a tag for management without changing the command line
> default? How about "management-default"? "recommended"? "latest"?
>