On Mon, Aug 26, 2024 at 11:04:47AM -0600, Alex Williamson wrote: > On Mon, 26 Aug 2024 07:16:37 +0000 > Manoj Vishwanathan <manojvishy@xxxxxxxxxx> wrote: > > > Hi maintainers, > > > > This RFC patch introduces the ability for userspace to control whether > > device (DMA) buffers are marked as cacheable, enabling them to utilize > > the system-level cache. > > > > The specific changes made in this patch are: > > > > * Introduce a new flag in `include/linux/iommu.h`: > > * `IOMMU_SYS_CACHE` - Indicates if the associated page should be cached in the system's cache hierarchy. > > * Add `VFIO_DMA_MAP_FLAG_SYS_CACHE` to `include/uapi/linux/vfio.h`: You'll need a much better description of what this is supposed to do when you resend it. IOMMU_CACHE already largely means that pages should be cached. So I don't know what ARM's "INC_OCACHE" actually is doing. Causing writes to land in a cache somewhere in hierarchy? Something platform specific? I have no idea. By your description it sounds similar to the x86 data placement stuff, whatever that was called, and the more modern TPH approach. Jason
