On Wed, 21 May 2003, Ralf Baechle wrote: > > There's really no such thing as "disabling" lwl/lwr. They are part > > of the base MIPS instruction set. If one wants to live without them, > > one can either rig a compiler to emit multi-instruction sequences instead > > of lwr/lwl to do the appropriate shifts and masks (which is slower on all > > targets), or you can rig the OS to emulate them, and hope that the processors > > lacking support will take clean reserved instruction traps, where the function > > can be emulated (which is "free" for code running on CPUs with lwl/lwr, > > but *really* slow for the guys doing emulation). > > Technically you're right ... In reality lwl/lwr are covered by US patent > 4,814,976 which would also cover a software implementation. So unless MIPS > grants a license for the purpose of emulation in the Linux kernel ... For practical reasons I believe it can be dealt with without patent infringing, but I am not that excited with doing anything at all about it. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
