RFC: cross-libkvm/libthread_db/proc_service

[Marcel Moolenaar]

All,

We have a couple of interfaces/APIs that can't be used cross-platform.

Take for example libkvm. On a 32-bit platform, we can't typically use
libkvm on a 64-kernel, because the libkvm interface uses u_long for
the target address, which on 32-bit platforms is 32 bits wide.

Likewise, libthread_db and proc_service are designed for native use
only and need API tweaks to work in a cross-environment. Both use
psaddr_t to represent a target address, which is defined as a void*
in <sys/procfs.h>.

I'd like to change those interfaces/APIs to allow them to be used in
a cross-platform debugging environment. Basically, this means that a
target address will have to be defined as a uint64_t. Other datatypes
may also need to be retyped.

For libkvm in particular I don't want to redefine struct kinfo_proc,
struct nlist, etc. While it could be useful in a hybrid 32/64-bit
environment, the effect of such changes have too high a chance to
trickle down various other components/interfaces. Thus, for libkvm
the focus is on kvm_read() and kvm_write().

Suggested plan of attack:
o  add kvm_xread() and kvm_xwrite() to the libkvm API to minimize
    the overall impact. The new functions operate on a 64-bit target
    address (psaddr_t).
o  change psaddr_t from a void* to a 64-bit integral (sys/procfs.h)
    This affects proc_service and libthread_db. And consequently our
    threading support in GDB.

Comments/thoughts?

-- 
Marcel Moolenaar
xcllnt at mac.com