* Questions about PCI resources in Linux 2.4.25 for MPC8260
@ 2004-11-25 9:59 Laurent Lagrange
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From: Laurent Lagrange @ 2004-11-25 9:59 UTC (permalink / raw)
To: linuxppc-embedded
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
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