Re: [9fans] Ultrasparc II

[John Packer <john@sockfarm.net>]

> As for different trap models, etc. in sparcs, it looks to me like all
> of that stuff is only visible in kernel mode, and the compilers don't
> generate the relevant instructions *now*, let alone for v9.  So adding
> the v9 instructions by hand to assembler source files or augmenting ka
> and kl should do the job; I don't think kc is involved.  Mixing old
> and new instructions is expected; that's the whole point of v9's
> compatibility with older sparc versions.  See the v9 spec. for the
> full story.
>
> The situation was different with 2c vs 1c (68020+ vs 68000): 2c was
> the older compiler and generated instructions and addressing modes not
> present in the 68000.

Sorry, I'm wasn't trying to complicate things.

By "compiler," I was referring the group kc, ka, and kl.

What I meant was, k[al] *do* generate instructions not
present in sparc v9, notably RETT, as well as read and writes
to the trap base register and other registers which no longer
exist, etc.

Maybe that is not such a big issue, but coupled with the
pointer handling, the changes in privileged registers, and
all the consequent changes to libmach, I thought it might be
simpler to branch off a new compiler-assembler-linker group,
rather than pepper the source "#ifdef sparcv9 " directives.