> -----Original Message-----
> From: Nicolin Chen <[email protected]>
> Sent: 29 December 2025 20:11
> To: Shameer Kolothum <[email protected]>
> Cc: [email protected]; [email protected];
> [email protected]; [email protected]; Nathan Chen
> <[email protected]>; Matt Ochs <[email protected]>; Jason Gunthorpe
> <[email protected]>; [email protected];
> [email protected]; [email protected]; Krishnakant Jaju
> <[email protected]>
> Subject: Re: [RFC PATCH 15/16] hw/arm/virt-acpi: Advertise Tegra241
> CMDQV nodes in DSDT
>
> On Wed, Dec 10, 2025 at 01:37:36PM +0000, Shameer Kolothum wrote:
> > +static int smmuv3_cmdqv_devices(Object *obj, void *opaque)
> > +{
> > + VirtMachineState *vms = VIRT_MACHINE(qdev_get_machine());
> > + GArray *sdev_blob = opaque;
> > + PlatformBusDevice *pbus;
> > + AcpiSMMUv3Dev sdev;
> > + SysBusDevice *sbdev;
> > +
> > + if (!object_dynamic_cast(obj, TYPE_ARM_SMMUV3)) {
> > + return 0;
> > + }
> > +
> > + if (!object_property_get_bool(obj, "tegra241-cmdqv", NULL)) {
> > + return 0;
> > + }
> > +
> > + pbus = PLATFORM_BUS_DEVICE(vms->platform_bus_dev);
> > + sbdev = SYS_BUS_DEVICE(obj);
> > + sdev.base = platform_bus_get_mmio_addr(pbus, sbdev, 1);
> > + sdev.base += vms->memmap[VIRT_PLATFORM_BUS].base;
> > + sdev.irq = platform_bus_get_irqn(pbus, sbdev, NUM_SMMU_IRQS);
> > + sdev.irq += vms->irqmap[VIRT_PLATFORM_BUS];
> > + sdev.irq += ARM_SPI_BASE;
> > + g_array_append_val(sdev_blob, sdev);
> > + return 0;
>
> This is pre-building SMMU's IORT nodes right? Maybe a different
> naming? And can be shared with the existing iort_smmuv3_devices?
Not really, if you are referring about this patch here,
https://github.com/NVIDIA/QEMU/commit/cc3b65e6a49a9b7addf44b377d4ef1de99bfee3f
I didn't find a clean way to store the pre-built smmuv3_devs other than
placing them in struct AcpiBuildTables. It's not clear we gain much by
restructuring things to populate and store them separately. At best,
it might slightly improve boot time, and if that becomes important we
can always add it as an optimization later.
This patch enumerates SMMUv3 accel instances with CMDQV separately, uses
that information to build the DSDT, and then frees the device array.
>
> We do so, because we need to link CMDQV's DSDT node to the SMMU's
> IORT node but it is created in build_iort() that is called after
> build_dsdt().
Hmm..not sure I get that. Does this mean IORT has a link to DSDT? I can't find
one..
Maybe I missed. Please let me know.
Thanks,
Shameer
