Re: pci express bar over 4gb

[Robert Hancock <hancockrwd@gmail.com>]

protagora27 protagora27 wrote:
> Hello Folks,
> 
> I have intel desktop board dx48bt2. I'm developing sw under linux
> 2.6.24  x86_64  for a pci express card ( pci express 2.0 compliant).
> I have to setup pci bar over 4 gb but bios uses value e0000000 as base
> address for pcie boards.
> I have seen that pciexbar is a register ( x48 chipset)  that decides
> where pcie boards are mapped inside memory map.

No, the PCIEXBAR register controls where the MMCONFIG aperture is mapped 
in memory. (It's a rather unfortunate name, I think, as it doesn't 
really have anything to do with PCI Express other than that you need to 
use MMCONFIG to access PCI Express extended configuration space).

> My goal is rewriting pcibar 0 e pcibar 1 with a value above 4gb. Maybe
>  I have  to rewrite pciexbar and then rewrite pci bar in my board.
> Questions:
> 1) can I rewrite  pciexbar  and where ?
> 2) can i rewrite pcibar 0 and 1 with a value over 4 gb
> 3) If i change bar 0 and bar 1 after linux startup have i to use hotplugging ?
> 
> Thanks
> 
> Luca