I believe, that even plain i486 have to be supported, also changelog claims that default should still be i486.yes, I think I did change that to avoid libgomp failures, which requires i586, and not just i486. Not sure what to do about that for squeeze.
Just document it in release notes/errata ?
$ apt-cache rdepends libgomp1 | wc -l 77 So all these packages would need setting of the -march flag explicitly. There are other packages which do require i586, like OpenJDK.
According to http://en.wikipedia.org/wiki/X86_instruction_listings#Added_with_Pentium the added instruction for pentium seems not be usually generated by gcc directly, may be CMPXCHG8B. Petr