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From: Ingo Molnar <mingo@kernel.org>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Dave Hansen <dave@sr71.net>,
	linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com,
	akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu,
	peterz@infradead.org, linux-next@vger.kernel.org, deller@gmx.de
Subject: Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field
Date: Mon, 29 Feb 2016 09:01:43 +0100	[thread overview]
Message-ID: <20160229080143.GB31950@gmail.com> (raw)
In-Reply-To: <20160228102629.0ef4ef4f@canb.auug.org.au>


* Stephen Rothwell <sfr@canb.auug.org.au> wrote:

> > u32?
> 
> It would have to be __u32, but we already use int and unsigned int
> extensively in the siginfo structure (which are both always assumed to
> be 32 bits).  So "unsigned int" probably makes most sense.

No. This whole mishap is an object lesson in why it's a bad idea to ever use ABI 
types outside of the __[us][8|16|32|64] space: some of them are 'fine', some of 
them (like longs) are not.

And we have to start somewhere, so we might as well start with new code that adds 
new ABI details: if a patch only uses __[us][8|16|32|64] types then it's easier to 
tell whether it's a safe ABI extension.

Thanks,

	Ingo

  parent reply	other threads:[~2016-02-29  8:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-26 17:34 [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Dave Hansen
2016-02-26 17:44 ` H. Peter Anvin
2016-02-26 22:10   ` Stephen Rothwell
2016-02-27 11:41     ` Ingo Molnar
2016-02-27 19:16       ` Dave Hansen
2016-02-27 19:35         ` H. Peter Anvin
2016-02-27 23:26           ` Stephen Rothwell
2016-02-27 23:40             ` [PATCH v2] signals, pkeys: make si_pkey 32 bits Stephen Rothwell
2016-02-29  7:57               ` Ingo Molnar
2016-02-29  8:01             ` Ingo Molnar [this message]
2016-02-29 22:54               ` [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell

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