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Re: [oc] i386 legally
Aloha!
When talking about processors and patents there are AFAIK (IANAL either ;-)
two separate issues to take note of here:
(1) IP-right related to the ISA.
(2) Implementation (i.e. micro architecture) specific patents.
In some cases there are functions directly related to (1) that are closely
tied to an implementation (2).
MIPS is a good example of (1), where the instructions for unaligned load and
store are protected. Lexra tried to bypass these IP-rights by generating an
exception whenever the opcodes for these instructions was found by the
instruction decoder. Unfortunately (in my opionion), the court considered a SW
implementation of the instructions to be equivalent to the HW solution and
Lexra lost the case.
http://www.mdronline.com/publications/epw/issues/epw_78.html
Just about everybody designing/implementing processors (including cores, DSP:s
etc) tries to patent smart design solutions (so did we at Ericsson too). For
those of you fortunate to have access to the Mircoprocessor Report magazine,
check the last pages in each issue for the latest patents. Everytime a new CPU
is released there is a flood of new patents covering ideas in the processor.
When Intel released the P4 they patented just about anything and thier sister
concerning trace caches. Both AMD and Intel have huge number of patents
concerning things like efficient decoupled instruction decode from x86 ISA to
uOPs, prefetch buffers and lots of other things. Digital/Compaq/HP have
patents from Alpha on SMT, wide issue reorder buffers able to clock at high
speeds, McFarlings famous hybrid branch predictors, VLIWs etc.
What I'm trying to say is that both the ISA in itself and implementation
details/functions needed to get good performance in a CPU implementing that
ISA might be covered by different types of IP rights. It's a mine field.
Some processor companies are more aggressive than others when it comes to
IP-rights. ARM and MIPS, being IP-core vendors are especially good at
protecting their IP-rights.
--
Med vänlig hälsning, Yours
Joachim Strömbergson - Alltid i harmonisk svängning.
VP, Research & Development
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