mmaping a fixed address fails on ARM

[Bryan Wu]

Let me add Andre here

Thanks,
-Bryan

On Thu, Jan 13, 2011 at 5:58 AM, Bryan Wu <bryan.wu at canonical.com> wrote:
> Hi Russell,
>
> Andre posted a mmap testcase [1] and a bug report [2] for Ubuntu
> kernel on OMAP4 system, since he is porting some applications from x86
> to ARM. He testcase works fine on x86, but always fail on ARM. I've
> tested it on OMAP3/OMAP4/i.MX51.
>
> Basically what he want to do is get a mapping on a specific virtual
> address. But AFAIK, mmap doesn't make sure we can get the mapping
> address as we want. On x86, it works fine. So if this fails, the
> application can't run on ARM.
>
> The implementation of arch_get_unmapped_area() is different from ARM
> and x86, that might makes mmap behavior different between ARM and x86.
> Andre said 2.6.28-versatile. I'm not sure whether it is a regression.
>
> [1]: http://launchpadlibrarian.net/61588086/main.c
> [2]: https://bugs.launchpad.net/ubuntu/+source/linux-ti-omap4/+bug/697004
>
> Thanks,
> --
> Bryan Wu <bryan.wu at canonical.com>
> Kernel Developer    +86.138-1617-6545 Mobile
> Ubuntu Kernel Team
> Canonical Ltd.      www.canonical.com
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>