On Fri, May 6, 2011 at 7:51 AM, Gordan Bobic <gordan@xxxxxxxxxx> wrote: > Matt Domsch wrote: >> On Wed, May 04, 2011 at 01:46:06PM -0500, Jon Masters wrote: >>> Folks, >>> >>> I'd like to kick off a discussion about flags for ARMv7. My proposal >>> here is that we treat v7hl as an entirely different architecture, and >>> don't try any multi-arch kind of hacks (there isn't the established user >>> base for Fedora ARM to justify doing any of those things at the moment). >>> >>> Things I think we should consider as a minimum: >>> >>> *). Little endian (obviously, but worth stating) (l) >>> *). Cortex-A8 or higher fully compliant core(s) >> >> Is there a measureable difference in code optimized for A8 vs A9 when >> running on A9? If so, my inclination would be to build for the future >> - A9. It's not like A9 hardware is hard to come by these days. > > I think the key thing to consider is cost/benefit. If the code optimized > for A9 runs poorly on A8, but the code optimized for A8 runs on A9 > almost as well as the code optimized for the A9, then it would be better > to optimize for the A8. > > Since A8 doesn't have OoOE, it wouldn't surprise me if latter was the > case (A8 code running imperceptibly worse on A9 but A9 code running > much worse on A8). > > There is also the more philosophical issue - A9 is already faster than > A8, so it may be better to target the A8 on the basis that it is more in > need of that extra boost. > > Having said that, the only real hardware platforms that are likely to be > affected here are the Genesi Efika and the Beagleboard. Everything else > that is popular seems to be either ARMv5 (Sheeva/Guru plugs) or A9 > (AC100, Pandaboard, Trimslice). Actually there's dozens of devices that use A8 processors. The Nokia n900 and dozens of other phones. They may or may not be desirable to support but there are a number of other tablet or netbook devices that would be nice to be able to use. Peter _______________________________________________ arm mailing list arm@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/arm
