Hi Drew, On 06/08/2026 06:23, Drew Fustini wrote: > On Tue, Jul 14, 2026 at 09:06:50PM +0800, Zhanpeng Zhang wrote: >> This RFC extends RISC-V CBQRI/resctrl support to external requesters >> behind a RISC-V IOMMU. > [..] >> Open questions for this RFC: >> >> * whether a common resctrl "devices" file is the right ABI for >> associating external requesters with a resource group; > > I think a separate file is the right approach to avoid confusing iommu > groups with pids. > > I should note that James Morse had an ARM MPAM "extras" tree [1] which > carried an iommu_group assignment interface, using the same > iommu_group:<id> format, but writing it to the tasks file. However, Ben > Horgan clarified back in March [2] in a reply to Qinxin Xia that it is > no longer maintained. Ben also wrote that the interface would likely > change upstream. I've added Ben Horgan and Qinxin Xia to the CC list so > hopefully they can chime in.
I haven't thought about the interface much but Reinette let me know here [1], with good reasons, that we should consider the format of the tasks file fixed. Thanks, Ben [1] https://lore.kernel.org/all/[email protected]/ > > I plan to review the patches in this series further but I didn't want to > delay any further in pointing out the above. > > Thanks, > Drew > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/snapshot%2Bextras/v6.18-rc1 > [2] > https://lore.kernel.org/lkml/[email protected]/
