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Message-ID: <20150708141500.GN1173@brightrain.aerifal.cx>
Date: Wed, 8 Jul 2015 10:15:00 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] Add PowerPC soft-float support

On Wed, Jul 08, 2015 at 01:59:58PM +0200, Felix Fietkau wrote:
> Some PowerPC CPUs (e.g. Freescale MPC85xx) have a completely different
> instruction set for floating point operations (SPE).
> Executing regular PowerPC floating point instructions results in
> "Illegal instruction" errors.
> 
> Until support for SPE FPU is added, make it possible to run these
> devices in soft-float mode.

I don't think musl can support it: according to Wikipedia it's not
IEEE conforming, but it seems to use integer registers, so if the
calling convention is soft-float-ABI compatible, you could build musl
with soft-float then use this broken FPU in callers that are able to
cope with "-ffast-math"-like brokenness.

The patch as sent is incomplete though. arch/powerpc/reloc.h would
need to define LDSO_ARCH for a soft-float ABI variant, and we need to
make sure that matches what's going in gcc.

Rich

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