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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Fri, 2 Sep 2016 22:02:35 +0100
Message-ID: <CAKv+Gu8NMVSgWqmVcgghX8iHjKSDAKe0S62ixD5uAppFZxdgcQ@mail.gmail.com>
To: Michael Zimmermann <sigmaepsilon92@gmail.com>
Cc: Laszlo Ersek <lersek@redhat.com>,
 "edk2-devel@lists.01.org" <edk2-devel@ml01.01.org>
Subject: Re: post-ExitBootServices memory protection of RT_Data (ARM)
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On 2 September 2016 at 21:45, Michael Zimmermann
<sigmaepsilon92@gmail.com> wrote:
> If I understand this correctly this is just some MMU feature, right?
> I'm talking about a pure ARM(with atag's) linux kernel which is not UEFI
> aware.
>
> Also the LinuxLoader disables almost everything(MMU, caches, it calls
> exitbootservices etc).
>
> I really can't explain technically what UEFI could have done to accomplish
> this protection with the MMU being disabled.
>

No, the kernel is entered with the MMU and caches off. The LinuxLoader
is a poorly maintained hack, and it is badly broken on AARCH64. On
ARM, however, it should still work. Does the system have an L2 cache
which may need invalidation/disabling?