I was informed that GDB recently broke for tracing 32bit applications in
64bit debugger on 64bit kernel.
There are at least 3 issues over here:
1. mknative does not include i386 files for x86_64 mode
_initialize_i386nbsd_tdep() and associated i386 GDB files are not
includes in the build
2. i386 C files are not buildable for amd64 environment as they pull
headers from machine/ and that is amd64/, not i386/. If we manually
include i386/ headers, they still pick machine/ files.
Including these files on amd64/ certainly never worked. And passing
types like void* cannot work as-is anyway.
3. There is not supported a translation between amd64 host registers
and i386 guest.
I've addressed locally 1 and 2, with the following scratch patch:
http://netbsd.org/~kamil/patch-00130-32bit-tracee-64bit-gdb.txt
For 3, I'm still unaware where is the root cause of invalid translation
between 64 and 32bit registers.
I've checked NetBSD 8.1 and its base GDB and this mode of tracing wasn't
supported either.. going backward in history predating 8.0 is not
promising at all due to a large number of ptrace(2) issues that were
addressed.
The conclusion is that there are several issues before getting it to
work and it doesn't look like any recent fallout.
Once we will cleanly handle 32bit files for 64bit debuggers in GDB
(patch mknative) and address 1. + 2. problems, I will resume this
process of investigation.
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