Re: [Qemu-devel] [PATCH v7 15/20] hw/arm/sysbus-fdt: Pass the VirtMachineState to the node creation functions

[Peter Maydell <peter.maydell@linaro.org>]

On 13 November 2017 at 13:00, Auger Eric <eric.auger@redhat.com> wrote:
> On 09/10/2017 19:47, Peter Maydell wrote:
>> More generally, why is sysbus-fdt involved in this at all?
>> I expected that instantiating and wiring up the SMMU would
>> be the job of hw/arm/virt.c, like any other device we
>> might have on the board.
> I wished to have the same type of option as for x86 where
> "-device intel-iommu" is passed to the QEMU command line. smmuv3 device
> being a SysBusDevice, a natural framework to handle its node creation
> function is sysbus-fdt. Having a -device approach is practical to pass
> other options to the device (this was typically the case for the
> "caching-mode" option). On Intel there are caching-mode, passthrough
> (pt) options.

Not being able to conveniently wire up a sysbus device on the
command line or pass it options are general problems. I don't
think the SMMU is a special case that should work around these
general issues by being created in a different way to everything
else. If the "hard to pass options to the device" problem needs
solving (which it does anyway if we want to drop '-net' for
configuring embedded ethernet devices) we should solve it,
not have some small set of sysbus devices be weirdly magic.

thanks
-- PMM