libbacktrace is a combination of libunwind and libexecinfo from
userland, configured for the boot loader. At the present time, the
symbol translation has been disabled from libexecinfo. This will produce
numeric backtraces, which can be helpful in producing automatic
backtraces for exceptional events (like null pointer dereference).
Doesn't work on powerpc, so not enabled on powerpc*. It wasn't obvious
why the same thing that worked elsewhere failed here, so punt until
someone with more powerpc fu can figure it out.
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