What is being setup in chrp_setup_pci_ptrs()?

What is being setup in chrp_setup_pci_ptrs()?

[Andrew_Klosterman]

Dear PCI Gurus,

     In the function chrp_setup_pci_ptrs() at the end of the file
/arch/ppc/kernel/chrp_pci.c there are three different variables that are
initialized depending on the system being used:
     pci_dram_offset,
     isa_mem_base and
     isa_io_base.

     Could someone please explain to me what the addresses these variables refer
to mean, please?

Many thanks,

--Andy



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Re: What is being setup in chrp_setup_pci_ptrs()?

[Geert Uytterhoeven]

On Mon, 9 Aug 1999 Andrew_Klosterman@3com.com wrote:
>      In the function chrp_setup_pci_ptrs() at the end of the file
> /arch/ppc/kernel/chrp_pci.c there are three different variables that are
> initialized depending on the system being used:
>      pci_dram_offset,
>      isa_mem_base and
>      isa_io_base.
> 
>      Could someone please explain to me what the addresses these variables refer
> to mean, please?

  - pci_dram_offset: address at which system memory starts when viewed from a
                     PCI device. CPU and PCI may have a different view to RAM.
  - isa_mem_base: address where the ISA memory space is located (first 1 MB on
		  a PC)
  - isa_io_base: address where the ISA I/O space is located (65536 I/O ports on
		 a PC)

Greetings,

						Geert

--
Geert Uytterhoeven                     Geert.Uytterhoeven@cs.kuleuven.ac.be
Wavelets, Linux/{m68k~Amiga,PPC~CHRP}  http://www.cs.kuleuven.ac.be/~geert/
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium


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Re: What is being setup in chrp_setup_pci_ptrs()?

[Adrian Cox]

Andrew_Klosterman@3com.com wrote:
>      In the function chrp_setup_pci_ptrs() at the end of the file
> /arch/ppc/kernel/chrp_pci.c there are three different variables that are
> initialized depending on the system being used:

>      pci_dram_offset,
The PCI address of physical memory address 0 (which should also be
kernel virtual address 0xc0000000). If physical memory does not start at
0, then things are a bit more complicated. 

>      isa_mem_base and
The kernel virtual address to which you have mapped ISA memory space.
You may need this for the ROMs on ISA cards.

>      isa_io_base.
The kernel virtual address to which you have mapped IO space. This is
used by insb and similar instructions.

For more details of these, read include/asm-ppc/io.h

- Adrian Cox, AG Electronics

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