Original 2.6.9 patch and explanation from somewhere within HP via
bugzilla...

ia64 stores a success/failure code in r10, and the return value (normal
return, or *positive* errno) in r8. The patch also sets the exit code to
negative errno if it's a failure result for consistency with other
architectures.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>