From: David Howells <dhowells@redhat.com>
To: "Mike Frysinger" <vapier.adi@gmail.com>
Cc: dhowells@redhat.com, "Greg Ungerer" <gerg@snapgear.com>,
"David McCullough" <David_Mccullough@securecomputing.com>,
LKML <linux-kernel@vger.kernel.org>,
"Bryan Wu" <Bryan.Wu@analog.com>,
"Bernd Schmidt" <bernds_cb1@t-online.de>,
"Robin Getz" <rgetz@blackfin.uclinux.org>
Subject: Re: nommu: handling anonymous mmap clearing in userspace rather than kernel
Date: Wed, 02 Apr 2008 15:20:14 +0100 [thread overview]
Message-ID: <5516.1207146014@redhat.com> (raw)
In-Reply-To: <8bd0f97a0804011434r4869fbe8t89ade12c04c97f2@mail.gmail.com>
Mike Frysinger <vapier.adi@gmail.com> wrote:
> a workaround: introduce a new no-mmu-only mmap flag MAP_UNINITIALIZE
> to signal to the kernel that it should skip the memset(). this way,
> userspace malloc() can do mmap(MAP_ANONYMOUS|MAP_UNINITIALIZE) to get
> large chunks of memory without affecting any other anonymous mmap()
> call.
I think that's reasonable for NOMMU. It's not like the process accessing the
uninitialised memory is prevented from accessing anything it wants to anyway.
I would vote that the memset() should only be skipped if requested as there
may be programs that call mmap(MAP_ANONYMOUS) expecting the memory they're
given to be zeroed out.
David
next prev parent reply other threads:[~2008-04-02 14:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-01 21:34 nommu: handling anonymous mmap clearing in userspace rather than kernel Mike Frysinger
2008-04-02 14:20 ` David Howells [this message]
2008-04-02 14:47 ` Mike Frysinger
2008-04-02 15:03 ` Bernd Schmidt
2008-04-02 15:07 ` Mike Frysinger
2008-04-03 11:06 ` Bernd Schmidt
2008-04-03 13:14 ` David Howells
2008-04-03 14:46 ` Mike Frysinger
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