Lexra

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Lexra did implement a 32-bit variant of the MIPS architecture for 32-bit microprocessors. Noteworthy architectural features are multithreading and the lack of the MIPS I instructions lwl, lwr, swl and swr that optimize the handling of unaligned loads.

Linux support

The instructions lwl, lwr, swl and swr are covered by US patent 4,814,976. Lexra therefore choose to implement these instructions by software emulation. In the 1999 - 2002 lawsuit of MIPS Technologies, Inc. vs. Lexra, Inc. about violation of this and a second patent the court ruled that Lexra's software implementation of these instructions was violating the patent. Which obviously means Linux can't emulate them either.

Technically support for Lexra processors without adding emulation of these instructions would be possible but the question is how much sense it would make as some software may rely on it fairly heavily.

Following the lawsuit Lexra became a MIPS32 license. MIPS later aquired Lexra. This resulted in the end of Lexra's former products and so at this time there also seems to be little interest in actually adding Linux support.

External links