dropbear fails on uClinux ARM NOMMU target with gcc-3.4.5 but not gcc-2.95.3

[Jamie Lokier]

Regarding dropbear 0.47 (not 0.43 as this thread started with), I have
seen consistent bus errors when compiling with the default options and
GCC 3.4.3 on an ARM CPU with no MMU.  (GCC from uclinux-tools-20050221).
I was unable to use Dropbear's client at all with this compiler.

GCC 2.95.3 for the same system was fine.

If I add the flag "-fno-strict-aliasing" to CFLAGS in Dropbear's
Makefile, then it seems to be fixed.  Well, so far I haven't seen any
of these bus errors.

If that is really fixing the problem, it indicates a type-aliasing
error in Dropbear or the associated libraries.  These errors can be
fixed by accessing the type-aliased memory through a union (as
described in the GCC manual), or with sufficiently recent GCC
versions, using the "may_alias" attribute.  Alternatively, simply
using "-fno-strict-aliasing" is fine although it suppress some
optimisation possibilities.  But look at it this way: the Linux kernel
uses that flag, so it can't be too bad.

Until they are fixed, I recommend adding -fno-strict-aliasing to
Dropbear's CFLAGS.  The flag is accepted by GCC 2.95 too, and I think
it's redundant with that version.

Enjoy,
-- Jamie