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From: "Laurent Lagrange" <lagrange@fr.oleane.com>
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Date: Thu, 25 Nov 2004 10:59:28 +0100
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Subject: Questions about PCI resources in Linux 2.4.25 for MPC8260
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Hi,

I ported a MPC8260 custom LSP from Linux 2.4.18 to Linux 2.4.25 and
I discovered something strange in the last kernel.

In the file arch/ppc/kernel/setup.c, the function "setup_arch" runs this new
code :

    code_resource.start   = virt_to_bus((void *)PAGE_OFFSET);
    code_resource.end    = virt_to_bus(&_etext)-1;
    data_resource.start   = virt_to_bus(&_etext);
    data_resource.end    = virt_to_bus(&_edata)-1;
    request_resource(&iomem_resource, &code_resource);
    request_resource(&iomem_resource, &data_resource);

This code seems to reserve PCI resources for the kernel code and data.

Has anybody an idea why these resources are added and needed ?
To detect future PCI conflicts ? To preserve from external PCI accesses ?

If the board sdram is not mapped on PCI at 0x00000000, these resources
generate problems when scanning pci bus and discovering sdram space
in own pci bridge header space.

Is there a new rule to set sdram board to 0x00000000 instead of 0x80000000
while enumerating PCI.

Thanks for your ideas.
 Laurent