On Thu, Mar 4, 2010 at 7:26 PM, Chris Tyler <chris@tylers.info> wrote:
On Thu, 2010-03-04 at 12:04 -0600, Adam Miller wrote:
> RAM is a really good point, I think it will be in the ballpark of 256
> (plus or minus a bit). Also, I'd like to open up the conversation
> about version of ARM we as a SIG want to support as the efforts start
> to ramp up while targeting popular devices. I think ARMv9 might be a
> little too aggressive but are there any devices that are still
> prominent that are ARMv5? Would it be possible (or even feasible) to
> maintain ARMv5, ARMv7, and ARMv9 in parallel and treat them as
> separate architectures?

The ARM "Family" vs. "Architecture" numbering is wonky (and very
frustrating - larger numbers don't reliably mean newer, bigger, faster,
or better). The SheevaPlug uses an "ARM9E" family chip, which uses the
"ARMv5TEJ" architecture. ARMv5 is a needed current target for that
device and others.

However, the popular Cortex chips use ARMv6M and ARMx7* architecture. Is
there enough performance difference to warrant targeting both
independently? And just the kernel, or userspace as well?

I'd been pondering Adam's exact question. It seems that Ubuntu (not that we should or need to follow what they do) decided upon supporting ARMv7 and later at their UDS [1]. There's also some other points here [2]. They also discussed a number of other worthwhile points to do with device trees and bootloaders which I presume are all relevant for discussions about support of Fedora on ARM platforms. But generally I've ignorant about the pros and cons of supporting the different artchitectures and I know there's discussion over THUMB vs no THUMB compile options as well. 


[1] http://lwn.net/Articles/364654/ 
[2] https://wiki.ubuntu.com/Mobile/ARMv7AndThumb