On Mon, 2012-09-17 at 21:36 +0100, Richard Sandiford wrote: > It's a hosted vs. embedded thing. Hosted targets like *-linux-gnu have > dynamic ABI requirements and so are keyed off an ABI rather than an > architecture. The only effect of -march= and --with-arch= should be to > extend the choice of available instructions. > > That was actually very useful in pre MIPS(isa)32 and MIPS(isa)64 days, > because MIPS IV had ISA extensions that could be used in 32-bit as well > as 64-bit code. You could therefore use the MIPS IV extensions with an > existing 32-bit MIPS I or MIPS II sysroot. The same sort of thing applied > to processor-specific extensions in 64-bit processors (of which there were > many :-)). It's less useful with the stock MIPS32 and MIPS64 ISAs because > the 32-bit subset of MIPS64 is (by design) essentially MIPS32.
If this is less useful now and since the multilib mips-mti-linux-gnu target I created earlier is only supporting the mips32(r2) and mips64(r2) ISAs (and not MIPS IV, etc) what do you think about me changing that target to default to n32 when specifying the mips64 or mips64r2 architectures and not specifying an explicit ABI? That way both the mips-mti-linux-gnu and mips-mti-elf targets will behave in the same way with regards to the default ABI. Steve Ellcey sell...@mips.com
