[MeeGo-dev] ARM softfloat or hardfloat?

[Zhang, Austin]

> The only concern is that it's binary incompatible (different ABI for fp
Seemed one big issue. 
Not sure if or not we can get some data on the gap between 'softfp' and 'hard'?

> In your other email, you wrote "For hard instead of softfp, with the update to gcc 4.5.0, it supports to do this". What did you mean by this?
Gcc doesn't support 'hard' combined with 'vfp' before 4.5.
Quote from 4.4 manual: "Using '-mfloat-abi=hard' with VFP coprocessors is not supported."
But 4.5 didn't have this limitation anymore.
CodeSourcery should backport this support from gcc 4.5 branch. 

-----Original Message-----
From: meego-dev-bounces at meego.com [mailto:meego-dev-bounces at meego.com] On Behalf Of Thiago Macieira
Sent: Thursday, August 05, 2010 9:24 PM
To: Development for the MeeGo Project (discussion list)
Subject: Re: [MeeGo-dev] ARM softfloat or hardfloat?

On Thursday 5. August 2010 02.25.40 Zhang, Austin wrote:
> So any concern on switch softfp to hard? Meanwhile, what compiler is 
> being used for Maemo 5 build? Does it support Neon naturally?
> 
> And as you may know, so far, we had switch compiler to 4.5.0, so 
> seemed it is also time to change those flags.

The only concern is that it's binary incompatible (different ABI for fp
parameters) from existing N900 applications. I don't know which way Harmattan would go -- Maemo5 backwards compatibility or MeeGo future compatibility.

The Maemo5 toolchain uses gcc 4.2, from the CodeSourcery release 2007q1 (I think). I think Harmattan upgraded to 2009q3, so gcc 4.3. Personally, I don't use either: I upgrade by downloading a new toolchain from CodeSourcery.

In your other email, you wrote "For hard instead of softfp, with the update to gcc 4.5.0, it supports to do this". What did you mean by this?

--
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
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