Embedded PowerPC with more than 2Go of RAM.

[Laurent Lagrange]

Hi all,

We want to design a PCI host embedded PowerPC board with a 3Go local RAM
memory.
This processor is a MPC74xx with an internal 32 bits and an external 36 bits
address bus.

Usually, the mapping is :
0x00000000-0x80000000 : physical RAM
0x80000000-0xc0000000 : PCI memory access
0xc0000000-0xf0000000 : kernel virtual memory
0xf0000000-0xffffffff : IO area access

1) On this board, the physical memory will be :
0x00000000-0xc0000000 : physical RAM
Where could we map PCI memory space ?

2) The kernel virtual memory usually has the same size as the physical RAM
(two memory footprint for the same physical space ! ).
The kernel virtual memory will be :
0xc0000000-0x180000000 : kernel virtual memory
Where could we map IO space ?

3) Usually, all the host memory is mapped on pci bus. For a 32bits pci bus,
we could not do this.
Is it possible to only map on pci, the DMA memory area which is managed with
the kmalloc(size, GFP_DMA)
and kfree functions ? How can we set the DMA memory parameters (base address
and size) ?

Thanks for any idea

Laurent