The s390 kernel maintainer is going to include the new system calls for PCI I/O memory access into the s390 Linux kernel. To make the final decision we would like to receive feedback from the libmlx4 and libibverbs user space library maintainers with direct answer to the question: will those system calls be used in the libmlx4 user space library to provide support for the s390x platform? This patch series contains the changes to kernel and users pace libraries required to provide support for the DAPL API on s390x platform. The current implementation of Infiniband verbs uses mapped memory areas to directly access the device UAR and Blueflame pages, which are located in the PCI I/O memory, from user space. On the s390x platform the PCI I/O memory can be accessed only using special privileged CPU instructions that cannot be used directly in user space programs. This restricts the usage of mapped memory areas to access the PCI I/O memory on s390x platform. This version of changes introduces two new kernel system calls which allow to execute the privileged CPU instructions in kernel space on request from user space programs. One system call allows the user space programs to write data to a PCI I/O memory page and the second one can be used to read data from PCI I/O memory to user space program buffer using mapped memory area addresses as arguments. This approach of the DAPL API support on s390x platform has the following advantages: * the current Infiniband and mlx4 support kernel modules remain unchanged; * the changes are separated into the special kernel platform specific directory; * no conditional compilation directives are used in the kernel source code; * no changes required to the kernel virtual memory management; * only minor changes are required in the user space DAPL API components. There are 1 patch for the Linux kernel and 2 patches for the DAPL API user space components. The kernel patch is not changed since the previous post and is included into this patch series just for reference. The patches for the perftest and dapl packages are not included into this series because those changes have been already applied to corresponding packages by the maintainers. [PATCH 1/3] s390/kernel: add system calls for access PCI memory This patch contains the new system call implementation required for the PCI I/O memory access from user space programs on s390x platform. [PATCH 2/3] libibverbs: add support for the s390x plaform This patch contains the changes to the libibverbs user space library to provide support of the s390x platform. [PATCH 3/3] libmlx4: add support for the s390x platform This patch contains the changes to the libmlx4 user space library intended to provide the PCI I/O memory access on the s390x platform. The direct access to mapped memory areas is replaced by appropriate system call invocation. Alexey Ishchuk (3): s390/kernel: add system calls for access PCI memory libibverbs: add s390x platform support libmlx4: add s390x platform support -- 1.8.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
