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From: Mike Frysinger <vapier.adi@gmail.com>
Date: Sat, 28 Nov 2009 13:47:26 -0500
Message-ID: <8bd0f97a0911281047i25626fc5q622e06fa1d306441@mail.gmail.com>
Subject: Re: [uClinux-dev] [PATCH] FDPIC: respect PT_GNU_STACK exec markings 
	when creating NOMMU stack
To: uClinux development list <uclinux-dev@uclinux.org>
Cc: David Howells <dhowells@redhat.com>,
       David McCullough <davidm@snapgear.com>, Greg Ungerer <gerg@uclinux.org>,
       Paul Mundt <lethal@linux-sh.org>,
       uclinux-dist-devel@blackfin.uclinux.org, linux-kernel@vger.kernel.org
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On Sat, Nov 28, 2009 at 10:24, Mike Frysinger wrote:
> The current code will load the stack size and markings, but then only use
> the markings in the MMU code path.  The NOMMU code path always passes EXEC
> to the mmap() call.  While this doesn't matter to most people during the
> run of the code, it causes a pointless icache flush when starting every
> FDPIC application and by default, that tends to be 128kB of waste.

for some raw numbers:
with my default FDPIC boot (inetd/syslog/watchdog), we icache flush
18,562,124 bytes.  with this stack fix, we cut off 3,538,944 bytes
(19% shrinkage).
-mike
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