svn commit: r246706 - head/lib/libc/arm/aeabi

[Nathan Whitehorn]

On 02/13/13 03:25, Andrew Turner wrote:
> On Tue, 12 Feb 2013 08:32:23 -0600
> Nathan Whitehorn <nwhitehorn at freebsd.org> wrote:
> 
>> A related question to these commits: are EABI binaries incompatible
>> with systems built for OABI? And vice versa? If so, should we mint a
>> new MACHINE_ARCH for ARM EABI (or OABI, I guess)? The usual
>> implication of sharing a uname -p string is that systems can run each
>> other's binaries -- that being broken is a strong argument for a new
>> value. -Nathan
> 
> Yes OABI and EABI are binary incompatible. The plan is to kill off OABI
> at some stage in the future when EABI is ready. At some time in the
> future I plan on flipping the switch to make EABI the default but keep
> OABI around to allow people a chance to update.
> 
> I am relying on ARM being a Tier 2 platform to change the ABI such that
> we break backward compatibility without changing uname -p. I have the
> start of a compat layer in the EABI project branch however never
> finished it. If people are interested in updating this compatibility
> layer I can point them at the code.
> 
> The other point is backwards compatibility should only be an issue for
> ARMv4 and ARMv5 as these are the only cores we have support for on the
> any of the current release branches. ARMv6 and ARMv7 is added to 10 and
> there has not been an MFC to any of the stable branches. Because of
> this I have even less hesitation to stitch the ABI for
> TARGET_ARCH=armv6.
> 
> In summary my plan is:
> < 9: No change
>> = 10: Switch to EABI and remove or depricate OABI
> 
> Andrew
> 

That all makes sense. Thanks for the explanation! If OABI were staying
around indefinitely, I think there would be a point to having a new
uname but not if it will be deprecated soon.
-Nathan