bootloader & head.S weirdness & restructuring
wd at denx.de
Fri Nov 26 23:06:21 EST 1999
In message <Pine.LNX.4.10.9911261032590.22448-100000 at opal.biophys.uni-duesseldorf.de>
Michael Schmitz wrote:
> > > > #if defined(CONFIG_x) || defined(CONFIG_y) || defined(CONFIG_z)
> > > > ...
> > > > #endif
> Plus it has the added benefit that you can still build kernels that
> support a range of hardware (by making has_feature_a not const 0 or 1 but
> something like feature_present(a) :-) If you don't need this, both are
> equivalent though.
This depends if the compiler has a chance to decide which code is
needed and which not. Otherwise it cannot optimize away dead code.
> Worried about wasting a few cycles on the branch? I've never noticed a
No, it's the code size that matters on many embedded systems. The
target is a minimal kernel code size. And improved performance is a
most welcome add-on.
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de
"...one of the main causes of the fall of the Roman Empire was that,
lacking zero, they had no way to indicate successful termination of
their C programs." - Robert Firth
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