Re: [PATCH] (Attempt to) Fix link compatibility check (was: Re:recent mips-elf linker "architecture ... incompatible" regressions)

[cgd at broadcom dot com]

At Fri, 15 Mar 2002 14:51:48 +0000 (UTC), "Thiemo Seufer" wrote:
> The patch below fixes at least some obvious cases. I'm not sure about
> the r4xxx compatibility, especially WRT r4010 which is defined as
> 64bit below but the disassembler calls it a MIPS II ISA. I also don't
> know how mips16 should be handled, there are 32bit and 64bit CPU's
> which implement the MIPS 16 extension.

* is it really desirable to be this picky linking together MIPS
binaries?

* is this going to cause problems when trying to link together
multiple which have been compiled specially (e.g. to use special
instructions for 'incompatible' CPUs, where detection is done at
run-time)?

* There really should be a relationship between mips32 (which is really
MIPS II ++) and the rest.

* before MIPS32 and MIPS64 the CP0 stuff wasn't "truly" standardized.
it seems wrong to differentiate based on that.

* More generally about CP0, if people are using cp0 ops, they really
should know what they can and can't link together, and the linker
shouldn't be trying to Help them, even by providing warnings.


Personally, I'd answer the first question as "no, it's not," and fall
back on simple tests based on, say, object file relocation size
compatibility, ABI stuff, etc.



chris