> -----Original Message----- > From: Daniel P. Berrangé <berra...@redhat.com> > Sent: Friday, May 9, 2025 9:14 AM > To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com> > Cc: Donald Dutile <ddut...@redhat.com>; Markus Armbruster > <arm...@redhat.com>; Shameer Kolothum via <qemu- > de...@nongnu.org>; qemu-...@nongnu.org; eric.au...@redhat.com; > peter.mayd...@linaro.org; j...@nvidia.com; nicol...@nvidia.com; > nath...@nvidia.com; mo...@nvidia.com; smost...@google.com; Linuxarm > <linux...@huawei.com>; Wangzhou (B) <wangzh...@hisilicon.com>; > jiangkunkun <jiangkun...@huawei.com>; Jonathan Cameron > <jonathan.came...@huawei.com>; zhangfei....@linaro.org > Subject: Re: [PATCH v2 1/6] hw/arm/smmuv3: Add support to associate a > PCIe RC >
[...] > > > - bus pcie, id=pcie.<num> > > > - device iommu=[intel_iommu|smmuv3|amd_iommu], bus=[sysbus | > > > pcie.<num>], id=iommu.<num> > > > [Yes, I'm sticking with 'iommu' as the generic naming... everyone thinks > of > > > device SMMUs as IOMMUs, > > > and QEMU should have a more arch-agnostic naming of these system > > > functions. ] > > > > Ok. But to circle back to what originally started this discussion—how > important > > is it to rely on the default "bus" in this case? As Markus pointed out, > SMMUv3 > > is a platform device on the sysbus, so its default bus type can’t point to > something > > like PCIe. QEMU doesn’t currently support that. > > > > The main motivation for using the default "bus" so far has been to have > better > > compatibility with libvirt. Would libvirt be flexible enough if we switched > to using > > something like a "primary-bus" property instead? > > Sorry if my previous comments misled you, when I previously talked about > linking via a "bus" property I was not considering the fact that "bus" > is a special property inside QEMU. From a libvirt POV we don't care what > the property is call - it was just intended to be a general illustration > of cross-referencing the iommu with the PCI bus it needed to be associated > with. Cool. That makes life easier 😊 Thanks, Shameer
