Re: [uClinux-dev] [PATCH] FDPIC: respect PT_GNU_STACK exec markings when creating NOMMU stack

From: Mike Frysinger
Date: Sat Nov 28 2009 - 13:47:50 EST


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. ÂThe NOMMU code path always passes EXEC
> to the mmap() call. ÂWhile 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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