Using my patches to gdb, I was able to examine ymm registers in test
programs using AVX under both i386 and amd64. Core dumps work for
both i386 and amd64 as well as for 32-bit binaries on amd64 (and
gdb can examine ymm regs for all 3 cases). gcore works in all 3
cases. Was able to modify a ymm register using 'set' in gdb at runtime
for both i386 and amd64. Note that gdb (neither in tree nor in
ports) cannot currently handle 32-bit binaries on amd64 since it is
missing a hook to force usage of ld-elf32.so.1.