On Wed, Jul 14, 2021 at 6:25 PM Joerg Roedel <j...@8bytes.org> wrote: > > On Tue, Jul 13, 2021 at 07:57:40PM -0400, Konrad Rzeszutek Wilk wrote: > > The SWIOTLB does have support to do late initialization (xen-pcifront > > does that for example - so if you add devices that can't do 64-bit it > > will allocate something like 4MB). > > That sounds like a way to evaluate. I suggest to allocate the SWIOTLB > memory at boot and when the IOMMUs are initialized we re-evaluate what > we ended up with and free the SWIOTLB memory if its not needed. > > If that turns out to be wrong during runtime (e.g. because a device is > switched to a passthrough default domain at runtime), we allocate a > small aperture for this device like the above mentioned 4MB.
I am currently working on this but I found that 4MB is not enough, 16MB is the minimal size to make the device work. How do I know the right SWIOTLB size for each device? > > (A boot option to always keep the aperture around might also be helpful > for some setups) OK, will also implement this in next iteration. Kai-Heng > > Regards, > > Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
