60 lines
2.3 KiB
Plaintext
60 lines
2.3 KiB
Plaintext
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Introduction
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============
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libmthca is a userspace driver for Mellanox InfiniBand HCAs. It works
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as a plug-in module for libibverbs that allows programs to use
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Mellanox hardware directly from userspace. See the libibverbs package
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for more information.
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Using libmthca
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==============
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libmthca will be loaded and used automatically by programs linked with
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libibverbs. The ib_mthca kernel module must be loaded for HCA devices
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to be detected and used.
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Supported Hardware
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==================
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libmthca currently supports HCAs based on the following Mellanox chips:
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MT23108 InfiniHost (PCI-X)
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MT25208 InfiniHost III Ex (PCI Express)
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MT25204 InfiniHost III Lx (PCI Express)
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Both non-DDR and DDR HCAs are supported, and the MT25208 is supported
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with both MT23108-compatible and native MemFree firmware.
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Valgrind Support
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================
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When running applications that use libibverbs under the Valgrind
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memory-checking debugger, Valgrind will falsely report "read from
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uninitialized" for memory that was initialized by the kernel drivers
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or HCA hardware. Specifically, Valgrind cannot see when kernel
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drivers or HCA hardware write to userspace memory, so when the process
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reads from that memory, Valgrind incorrectly assumes that the memory
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contents are uninitialized, and therefore raises a warning.
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libmthca can be built with specific support for the Valgrind
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memory-checking debugger by specifying the --with-valgrind command
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line argument to configure. This flag enables code in libibverbs to
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tell Valgrind "this memory may look uninitialized, but it's really
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OK," which therefore suppresses the incorrect "read from
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uninitialized" warnings. This code adds trivial overhead to the
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critical performance path, so it is disabled by default. The intent
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is that production users can use a "normal" build of libmthca and
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developers can use the "valgrind debug" build by simply switching
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their OPENIB_DRIVER_PATH environment variables.
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Libmthca needs some header files from Valgrind in order to compile
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this support; it is important to use the header files from the same
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version of Valgrind that will be used at run time. You may need to
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specify the directory where Valgrind's header files are installed as
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an argument to --with-valgrind. For example
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./configure --with-valgrind=/opt/valgrind
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will make the libmthca build look for valgrind headers in
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/opt/valgrind/include
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