From: Arnd Bergmann <arnd@arndb.de>
To: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] unicore32 fix: remove arch-specific futex support
Date: Wed, 30 Mar 2011 14:40:03 +0200
User-Agent: KMail/1.12.2 (Linux/2.6.37; KDE/4.3.2; x86_64; ; )
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>, Paul Mundt <lethal@linux-sh.org>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
References: <01eb01cbeeb7$30390460$90ab0d20$@mprc.pku.edu.cn> <201103301417.20027.arnd@arndb.de> <alpine.LFD.2.00.1103301421390.22418@localhost6.localdomain6>
In-Reply-To: <alpine.LFD.2.00.1103301421390.22418@localhost6.localdomain6>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Message-Id: <201103301440.03479.arnd@arndb.de>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 731
Lines: 21

On Wednesday 30 March 2011, Thomas Gleixner wrote:
> The problem is that you need cmpxchg in user space as well.
> 
> ARM does this with some syscall magic for machines which do not have
> cmpxchg.

Ah, right. I wonder how sh does it.

I also remember that the original unicore32 ABI had support for a cmpxchg
system call, but that was removed with the move to the generic syscall
table.

It is of course possible to add it back using the __NR_arch_specific_syscall
entry point.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/