From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] x86_64: Implement personality ADDR_LIMIT_32BIT
Date: Mon, 6 Oct 2008 12:17:14 +0300 [thread overview]
Message-ID: <20081006091709.GB20852@localhost.localdomain> (raw)
In-Reply-To: <20081006084246.GC3180@one.firstfloor.org>
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On Mon, Oct 06, 2008 at 10:42:46AM +0200, Andi Kleen wrote:
> On Mon, Oct 06, 2008 at 11:17:23AM +0300, Kirill A. Shutemov wrote:
> > On Mon, Oct 06, 2008 at 08:13:19AM +0200, Andi Kleen wrote:
> > > Unfortunately that doesn't work for shmat() because the address argument
> > > is not a search hint, but a fixed address.
> > >
> > > I presume you need this for the qemu syscall emulation. For a standard
> > > application I would just recommend to use mmap with tmpfs instead
> > > (sysv shm is kind of obsolete). For shmat() emulation the cleanest way
> > > would be probably to add a new flag to shmat() that says that address
> > > is a search hint, not a fixed address. Then implement it the way recommended
> > > above.
> >
> > I prefer one handle to switch application to 32-bit address mode. Why is it
> > wrong?
>
> "32 bit mode" really has to be set at exec time, otherwise it is not
> (e.g. the stack will be beyond).
Stack isn't a problem for qemu. qemu allocate stack for target application
by itself.
> And personality() is not thread local/safe, so it's not a particularly
> good interface to use later.
qemu can call personality() before any threads will be created.
> Per system call switches are preferable
> and more flexible.
Per syscall switches are cool, but I don't see any advantage from it for
qemu.
--
Regards, Kirill A. Shutemov
+ Belarus, Minsk
+ ALT Linux Team, http://www.altlinux.com/
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next prev parent reply other threads:[~2008-10-06 9:16 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-03 7:04 [PATCH] x86_64: Implement personality ADDR_LIMIT_32BIT Kirill A. Shutemov
2008-10-03 8:02 ` Ingo Molnar
2008-10-03 9:25 ` Kirill A. Shutemov
2008-10-03 12:44 ` Arjan van de Ven
2008-10-03 12:58 ` Kirill A. Shutemov
2008-10-06 6:13 ` Andi Kleen
2008-10-06 8:17 ` Kirill A. Shutemov
2008-10-06 8:42 ` Andi Kleen
2008-10-06 9:17 ` Kirill A. Shutemov [this message]
2008-10-06 9:56 ` Andi Kleen
2008-10-06 10:12 ` Kirill A. Shutemov
2008-10-06 13:26 ` Andi Kleen
2008-10-06 14:37 ` [PATCH, RFC] shmat: introduce flag SHM_MAP_HINT Kirill A. Shutemov
2008-10-06 19:29 ` Andi Kleen
2008-10-07 6:57 ` Kirill A. Shutemov
2008-10-07 6:57 ` [PATCH, RFC, v2] " Kirill A. Shutemov
2008-10-07 8:20 ` Andi Kleen
2008-10-07 10:09 ` Kirill A. Shutemov
2008-10-07 11:26 ` Andi Kleen
2008-10-07 11:23 ` Kirill A. Shutemov
2008-10-07 14:38 ` Hugh Dickins
2008-10-07 15:10 ` Andi Kleen
2008-10-07 11:08 ` [PATCH, RFC] " KOSAKI Motohiro
2008-10-07 11:21 ` Andi Kleen
2008-10-07 11:21 ` Kirill A. Shutemov
2008-10-07 11:26 ` KOSAKI Motohiro
2008-10-07 11:30 ` Kirill A. Shutemov
2008-10-07 11:50 ` Andi Kleen
2008-10-07 11:24 ` Kirill A. Shutemov
2008-10-07 12:31 ` Alan Cox
2008-10-07 13:14 ` Andi Kleen
2008-10-03 9:33 ` [PATCH] x86_64: Implement personality ADDR_LIMIT_32BIT Kirill A. Shutemov
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