Re: [Qemu-devel] [PATCH v4 0/6] machvirt dynamic sysbus device instantiation

[Alexander Graf]

On 31.10.14 14:53, Eric Auger wrote:
> This patch series enables machvirt to dynamically instantiate sysbus
> devices from command line (using -device option).
> 
> All those sysbus devices are plugged onto a platform bus. This latter
> device is instantiated in machvirt and takes care of the binding of
> children sysbus devices on a machine init done notifier. The device
> tree node generation for children dynamic sysbus device also happens
> on a subsequent notifier that must be executed after the above one.
> machvirt registers that notifier before the platform bus creation to
> make sure notifiers are executed in the right order: dt generation
> after actual QOM binding.
> 
> Very few sysbus devices are supposed to be instantiated that way.
> VFIO devices belong to them.
> 
> Node creation really is architecture specific. On ARM the dynamic
> sysbus device node creation is implemented in a new C module,
> hw/arm/sysbus-fdt.c and not in the machine file.
> 
> This series applies on top of Alex Graf's series
> [PATCH v3 0/7] Dynamic sysbus device allocation support
> http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg04860.html
> 
> Machvirt transformations and sysbus-fdt are largely inspired from Alex work.
> 
> The patch series can be found at:
> http://git.linaro.org/people/eric.auger/qemu.git (branch vfio_integ_v7)

Overall the approach looks sane to me. I'm not 100% convinced it's a
good idea to make the fdt generation "arm generic", but I'll leave that
for Peter to decide. On PPC this definitely wouldn't fly with all the
different subarchs. I'm not sure whether ARM is more standardized on the
device tree generation, especially with different #address-size
properties and the likes.


Alex