In that case, I guess this should be OK for now, as MXU support is initiated by Craig and this will be
an easy add-on when he provide necessary information. Reviewed-by: Stefan Markovic <smarko...@wavecomp.com> On 28.10.18. 19:39, Aleksandar Markovic wrote: >> Subject: Re: [PATCH v7 04/20] target/mips: Add and integrate MXU decoding >> engine > placeholder >> >>> Is the best way to implement this to include processing of MUL, CLZ, >>> CLO, SDBBP instructions into decode_opc_mxu as their encodings aren't >>> overlaid by MXU instructions considering MIPS SPECIAL2 instruction >>> pool and MXU Instruction Set? >> The problem is that we don't have the documentation for Ingenic's base >> instruction set. My understanding is that Craig established necessity of >> including non-MXU MUL into decode_opc_mxu() by experimentation, >> or by looking at Ingenic's toolchain source code. >> >> Note that CLZ, CLO, SDBBP are moved from SPECIAL2 to another >> place in opcode space in MIPS R6. >> >> Craig, can you offer any insight on CLZ, CLO, SDBBP in Ingenic's base >> instruction set? They are in SPECIAL2 opcode space for MIPS pre-R6. >> >> Worse come to worst, I recommend adding "TODO" comment to an >> appropriate place in decode_opc_mxu(), and go forward without handling >> CLZ, CLO, SDBBP - given that all changes in this series are just the first >> phase of implementing MXU support - they won't affect any production >> code at this moment. >> > I think this comment should be added to the decode_opc_mxu(), within patch 11: > > /* > * TODO: Investigate necessity of including handling of > * CLZ, CLO, SDBB in this function, as they belong to > * SPECIAL2 opcode space for regular pre-R6 MIPS ISAs. > */ > > Thanks, > Aleksandar