Re: [RFC 04/20] iommu: Add iommu_device_get_info interface

[Lu Baolu]

On 2021/9/29 17:25, Lu Baolu wrote:
> Hi David,
>
> On 2021/9/29 10:52, David Gibson wrote:
> > On Sun, Sep 19, 2021 at 02:38:32PM +0800, Liu Yi L wrote:
> > > From: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
> > >
> > > This provides an interface for upper layers to get the per-device iommu
> > > attributes.
> > >
> > >      int iommu_device_get_info(struct device *dev,
> > >                                enum iommu_devattr attr, void *data);
> > That fact that this interface doesn't let you know how to size the
> > data buffer, other than by just knowing the right size for each attr
> > concerns me.
>
> We plan to address this by following the comments here.
>
> https://lore.kernel.org/linux-iommu/20210921161930.GP327412@xxxxxxxxxx/

And Christoph gave another option as well.

https://lore.kernel.org/linux-iommu/20210922050746.GA12921@xxxxxx/

Best regards,
baolu