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libmlx4.spec.in | ||
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mlx4.driver | ||
README |
Introduction ============ libmlx4 is a userspace driver for Mellanox ConnectX InfiniBand HCAs. It is a plug-in module for libibverbs that allows programs to use Mellanox hardware directly from userspace. See the libibverbs package for more information. Using libmlx4 ============== libmlx4 will be loaded and used automatically by programs linked with libibverbs. The mlx4_ib kernel module must be loaded for HCA devices to be detected and used. Supported Hardware ================== libmlx4 currently supports HCAs based on the following Mellanox chip: MT25408 ConnectX (PCI Express) These HCAs use the mlx4_ib kernel driver. Support for other Mellanox HCAs, which use the ib_mthca kernel driver, is provided by the libmthca userspace driver. Valgrind Support ================ When running applications that use libibverbs under the Valgrind memory-checking debugger, Valgrind will falsely report "read from uninitialized" for memory that was initialized by the kernel drivers or HCA hardware. Specifically, Valgrind cannot see when kernel drivers or HCA hardware write to userspace memory, so when the process reads from that memory, Valgrind incorrectly assumes that the memory contents are uninitialized, and therefore raises a warning. libmlx4 can be built with specific support for the Valgrind memory-checking debugger by specifying the --with-valgrind command line argument to configure. This flag enables code in libibverbs to tell Valgrind "this memory may look uninitialized, but it's really OK," which therefore suppresses the incorrect "read from uninitialized" warnings. This code adds trivial overhead to the critical performance path, so it is disabled by default. The intent is that production users can use a "normal" build of libmlx4 and developers can use the "valgrind debug" build by simply switching their OPENIB_DRIVER_PATH environment variables. Libmlx4 needs some header files from Valgrind in order to compile this support; it is important to use the header files from the same version of Valgrind that will be used at run time. You may need to specify the directory where Valgrind's header files are installed as an argument to --with-valgrind. For example ./configure --with-valgrind=/opt/valgrind will make the libmlx4 build look for valgrind headers in /opt/valgrind/include