Re: [PATCH v2 4/6] arm/dt: probe for platforms via the device tree

On Mon, 31 Jan 2011, Grant Likely wrote:

If a dtb is passed to the kernel then the kernel needs to iterate
through compiled-in mdescs looking for one that matches and move the
dtb data to a safe location before it gets accidentally overwritten by
the kernel.

This patch creates a new function, setup_machine_fdt() which is
analogous to the setup_machine_atags() created in the previous patch.
It does all the early setup needed to use a device tree machine
description.  It also creates arm_unflatten_device_tree() which copies
the dtb into an allocated buffer and unflattens it into the live-tree
representation.

v2: Changed to save the dtb by copying into an allocated buffer.
    - Since the dtb will very likely be passed in the first 16k of ram
      where the interrupt vectors live, memblock_reserve() is
      insufficient to protect the dtb data.

This is wrong.  The vector page can be allocated anywhere.  It is 
currently allocated with memblock_alloc(), so if you memblock_reserve() 
the dtb soon enough then it should be safe and the vector page or 
whatever will be allocated somewhere else.

What was the actual problem?


Nicolas