Re: [rfc] trad-frame change

[Andrew Cagney <cagney@gnu.org>]

> There are four kinds of signal frames on MIPS/Linux that we have to
> recognize:
>   - o32 sigreturn
>   - o32 rt_sigreturn
>   - n32 rt_sigreturn
>   - n64 rt_sigreturn
> 
> They're all basically the same but the offsets differ.  Kind could be
> moved out of the cache, I think, since it isn't used after the cache is
> filled.  So I could use your new mechanism after all.

So there are really two variants - o32sigreturn and rt_sigreturn (with 
constants computed from the architecture vector)?

> What would _really_ be nice would be a way to pass the kind from the
> sniffer (which really just calls PC_IN_SIGTRAMP) to the frame creation
> code... not have to read inferior memory to figure out which it is,
> twice.

I'll think about that, I may need to change the unwinder object anyway.

Just remember that it is the number of unique addresses accessed (0 vs 1 
vs 2 ...) and not the number of times each address is accessed that is 
going to be important - multiple accesses to a single address can be 
handled with a cache.

Andrew