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Wed, 23 Sep 2026 10:24:52 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1x9QiB-0000000EA0Z-20hw; Wed, 23 Sep 2026 14:24:51 -0300 Date: Wed, 23 Sep 2026 14:24:51 -0300 From: Jason Gunthorpe To: James Morse Cc: "Luck, Tony" , alex@ghiti.fr, aou@eecs.berkeley.edu, babu.moger@amd.com, baolin.wang@linux.alibaba.com, ben.horgan@arm.com, corbet@lwn.net, cuiyunhui@bytedance.com, Dave.Martin@arm.com, fustini@kernel.org, joro@8bytes.org, kevin.tian@intel.com, palmer@dabbelt.com, pjw@kernel.org, reinette.chatre@intel.com, robin.murphy@arm.com, shuah@kernel.org, tomasz.jeznach@linux.dev, wangzhou1@hisilicon.com, will@kernel.org, xiaqinxin@huawei.com, yuanzhu@bytedance.com, zengheng4@huawei.com, zhangzhanpeng.jasper@bytedance.com, x86@kernel.org, iommu@lists.linux.dev, linuxarm@huawei.com, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: Resctrl and I/O Message-ID: <20260923172451.GN1540250@ziepe.ca> References: <8557363f-c051-4267-9fbc-f4cbb13ac35e@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8557363f-c051-4267-9fbc-f4cbb13ac35e@arm.com> On Wed, Sep 23, 2026 at 06:13:27PM +0100, James Morse wrote: > Using iommu_group like this may need a bit more thinking.... > If we can fall back to using a device as seen by sysfs, then the arch differences > here could be invisible to user-space. Please don't codify iommu_groups in any new uAPI, that has proven to be a problematic choice for VFIO. We undid it.. Lets not repeat it. Jason