>-----Original Message----- >From: Cédric Le Goater <c...@redhat.com> >Sent: Wednesday, September 20, 2023 8:20 PM >Subject: Re: [PATCH v1 15/22] Add iommufd configure option > >On 9/20/23 05:42, Duan, Zhenzhong wrote: >> >> >>> -----Original Message----- >>> From: Cédric Le Goater <c...@redhat.com> >>> Sent: Wednesday, September 20, 2023 1:08 AM >>> Subject: Re: [PATCH v1 15/22] Add iommufd configure option >>> >>> On 8/30/23 12:37, Zhenzhong Duan wrote: >>>> This adds "--enable-iommufd/--disable-iommufd" to enable or disable >>>> iommufd support, enabled by default. >>> >>> Why would someone want to disable support at compile time ? It might >> >> For those users who only want to support legacy container feature? >> Let me know if you still prefer to drop this patch, I'm fine with that. > >I think it is too early. > >>> have been useful for dev but now QEMU should self-adjust at runtime >>> depending only on the host capabilities AFAIUI. Am I missing something ? >> >> IOMMUFD doesn't support all features of legacy container, so QEMU >> doesn't self-adjust at runtime by checking if host supports IOMMUFD. >> We need to specify it explicitly to use IOMMUFD as below: >> >> -object iommufd,id=iommufd0 >> -device vfio-pci,host=0000:02:00.0,iommufd=iommufd0 > >OK. I am not sure this is the correct interface yet. At first glance, >I wouldn't introduce a new object for a simple backend depending on a >kernel interface. I would tend to prefer a "iommu-something" property >of the vfio-pci device with string values: "legacy", "iommufd", "default" >and define the various interfaces (the ops you proposed) for each >depending on the user preference and the capabilities of the host and >possibly the device. > >I might be wrong and this might have been discussed before. If so, it >should go in the cover letter with other things : what is this patchset >providing to VFIO (multiple iommu backends), how it is reaching that >goal, how is it organized, how do we deal with the special case (spapr), >what's the user interface, etc.
Got it, I'll add " how is it organized, how do we deal with the special case (spapr)" part, other parts seems already in cover letter, there is a diagram showing the architecture of VFIO/legacy BE/IOMMUFD BE, etc. Thanks Zhenzhong
