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Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Andrew Lunn , Gerd Hoffmann , Vivek Kasireddy , Sumit Semwal , Christian =?iso-8859-1?Q?K=F6nig?= , Shuah Khan , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kselftest@vger.kernel.org, sdf@fomichev.me, razor@blackwall.org, daniel@iogearbox.net, almasrymina@google.com, matttbe@kernel.org, skhawaja@google.com, dw@davidwei.uk, Bobby Eshleman Subject: Re: [PATCH net-next 3/4] selftests/net: ncdevmem: add -b option to set rx-buf-size on bind Message-ID: References: <20260603-tcpdm-large-niovs-v1-0-f37a4ac6726c@meta.com> <20260603-tcpdm-large-niovs-v1-3-f37a4ac6726c@meta.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: On Fri, Jun 05, 2026 at 08:35:25AM -0700, Stanislav Fomichev wrote: > On 06/03, Bobby Eshleman wrote: > > From: Bobby Eshleman > > > > Add -b to request a non-default niov size via > > NETDEV_A_DMABUF_RX_BUF_SIZE. When the value exceeds PAGE_SIZE, > > udmabuf_alloc() switches to an MFD_HUGETLB-backed memfd so each 2 MB > > hugepage produces one naturally-aligned sg entry. > > > > Reject values > 2 MB up front: MFD_HUGETLB + udmabuf can only guarantee > > 2 MB per sg entry (one hugepage), so a larger rx_buf_size would fail the > > per-sg length/alignment check. > > > > Add CONFIG_HUGETLBFS=y to drivers/net/hw/config so the new path is > > reachable in the CI kernels built for these tests. > > I vaguely remember there was also some kernel cmdline argument to > reserve these? Do we need to also do something to NIPA to reserve 2MB > pages for this test? Or was it for 1GB pages? Good call, my little runner script when prototyping this adds these pages at runtime and I forgot to move it into the patch, we can have the py runner do this setup. Best, Bobby