linux-kernel - Re: [PATCH 02/10] x86, asm: use bool for bitops and other assembly outputs

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Message-ID: <20160608090111.GA11390@gmail.com>
Date:	Wed, 8 Jun 2016 11:01:12 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 02/10] x86, asm: use bool for bitops and other assembly
 outputs


* H. Peter Anvin <hpa@...or.com> wrote:

> On 06/08/16 01:33, Ingo Molnar wrote:
> > 
> > Note that this particular build error was introduced by b0bdba9825fe, a later 
> > patch in this series - but in generaly I'm uneasy about allowing function 
> > signatures diverge between architectures.
> > 
> 
> For the bitops, they already do: PowerPC, for example, have "unsigned
> long" in places where x86 has "int".  This is obviously undesirable, but
> apparently we have not found it enough of a problem to deal with.
>
> One could easily argue the ppc definition is the better one; I was myself 
> considering promoting the x86 side to "long" to handle enormous bitmaps. At the 
> same time, it is hard to avoid the fact that ppc has unsigned bitops operations 
> and x86 has signed ones when they are both native instructions.

That's a divergence with an underlying reason - but not harmonizing the return 
code is an unforced error AFAICS and can be fixed.

Thanks,

	Ingo