RE: [PATCH v1 15/22] Add iommufd configure option

[Duan, Zhenzhong]

>-----Original Message-----
>From: Cédric Le Goater <clg@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.

>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

Thanks
Zhenzhong