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Re: [Qemu-devel] [PATCH] hw/arm/boot: Increase fdt alignment
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH] hw/arm/boot: Increase fdt alignment |
Date: |
Wed, 15 Jul 2015 17:45:23 +0100 |
On 13 July 2015 at 17:50, Alexander Graf <address@hidden> wrote:
> The Linux kernel on aarch64 creates a page table entry at early bootup
> that spans the 2MB range on memory spanning the fdt start address:
>
> [ ALIGN_DOWN(fdt, 2MB) ... ALIGN_DOWN(fdt, 2MB) + 2MB ]
>
> This means that when our current 4k alignment happens to fall at the end
> of the aligned region, Linux tries to access memory that is not mapped.
>
> The easy fix is to instead increase the alignment to 2MB, making Linux's
> logic always succeed.
>
> We leave the existing 4k alignment for 32bit kernels to not cause any
> regressions due to space constraints.
...did you report the kernel bug?
thanks
-- PMM