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gregset vs prgregset vs elf_gregset in thread_db


The thread-db routines are defined to take arguments of type 'prgregset_t'. 
On about half the supported architectures, prgregset_t is typedef'd to be
'gregset_t'; on the other half it is 'elf_gregset_t'.  I don't know where
the gregset_t definitions came from, especially on platforms that have
always been ELF, but they are substantially less useful than their elf
counterparts - what we really want to fill in is the data we can get from
ptrace, and pt_regs is usually fairly similar to an elf_gregset_t and an
elf_fpregset_t.

For instance, on PowerPC the NIP is not in any of r0 - r31, and a gregset_t
only has 32 elements.  No way to convey the thread's NIP, which makes
debugging all but meaningless.

The only consumer of the prgregset_t and prfpregset_t types is thread-db. 
Is there any objection to changing them to the elf_* variants, and possibly
bumping the thread-db soname?  Although I'm not sure the latter is even
necessary; gdb is the only consumer of thread-db I've ever found on linux,
and it doesn't work with threads on the architectures affected yet anyway.

-- 
Daniel Jacobowitz                           Debian GNU/Linux Developer
Monta Vista Software                              Debian Security Team


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