Merging 64 bit changes to -HEAD - part 3

[M. Warner Losh]

In message: <AANLkTikv__dQnu3iEMl-Of2xzJc6xoPSCrEpLz5GVg6R at mail.gmail.com>
            "Jayachandran C." <c.jayachandran at gmail.com> writes:
: On Tue, Jun 22, 2010 at 4:10 AM, M. Warner Losh <imp at bsdimp.com> wrote:
: > The changes to asm.h change the ABI for all ABIs, no?  Does that
: > matter?  The jumpbuf is a user-visible thing...  I'm guessing that we
: > can say it is OK, but it sure would be nice if we could MFC this
: > change before 8.1-RELEASE (but given the locked-down nature of the
: > tree, I'm not hopeful).
: 
: Currently, it should not disturb the o32 ABI, since it is inside an ifdef.
: In n32/n64 the jmpbuf entries are 64bit and we will use one more
: register for GP.

Good point.  I missed that when I was looking at it.  My bad.a

: Slightly off-topic,  _JBLEN is 95 for mips, I cannot see a reason for
: this value, any hints?

Hmmm.  31 normal registers (we don't save $0 :).  32 floating point
registers that are double size.  31 + 2 * 32 == 95.  Maybe that's
why...

There's at least one Mips that has CP1 registers for its specialized
hardware.  If we ever are going to support saving/restoring that state
along with the core and FP registers, we will need to expand this...

Warner