PCIe IOMEM Resource Allocation

PCIe IOMEM Resource Allocation

[John]

Hi
I am trying to write a PCIe linux device driver to handle PCIe switches and
endpoints that show up after the Redhat 6.4 linux is already up and running.

If I try to allocate the resources of the PCIe switches & endpoints between
0xF4000000 and 0xF47FFFFF everything works fine .. But this range is quite
full with other devices, so I tried to extend this range to start from
0xF0000000, or from 0xD0000000 the allocation works fine, but I am unable to
access devices in the extended range

Anybody has idea why I am unable to use the complete 3G - 4G address range ?
Is it related to some ACPI boot configuration that need to be changed, I can
see in my dmesg

pci_root PNP0A08:00: host bridge window [mem 0xf4000000-0xf7ffffff]
pci_root PNP0A08:00: host bridge window [io 0x1000-0x7fff]
pci_root PNP0A08:00: host bridge window [io 0x0000-0x03af]
pci_root PNP0A08:00: host bridge window [io 0x03e0-0x0cf7]
pci_root PNP0A08:00: host bridge window [io 0x0d00-0x0fff]
pci_root PNP0A08:00: host bridge window [mem 0xfed00000-0xfed03fff]
pci_root PNP0A08:00: host bridge window [mem 0xfed40000-0xfed44fff]
pci_root PNP0A08:00: host bridge window [io 0x03b0-0x03bb]
pci_root PNP0A08:00: host bridge window [io 0x03c0-0x03df]
pci_root PNP0A08:00: host bridge window [mem 0x000a0000-0x000bffff]
pci_root PNP0A08:01: host bridge window [mem 0xf8000000-0xfbffffff]
pci_root PNP0A08:01: host bridge window [io 0x8000-0xffff]

Is there a reason for this limited range ? Is it processor dependant ?

Thanks 

Re: PCIe IOMEM Resource Allocation

[Yijing Wang]

On 2014/7/24 14:35, John wrote:
> Hi
> I am trying to write a PCIe linux device driver to handle PCIe switches and
> endpoints that show up after the Redhat 6.4 linux is already up and running.
> 
> If I try to allocate the resources of the PCIe switches & endpoints between
> 0xF4000000 and 0xF47FFFFF everything works fine .. But this range is quite
> full with other devices, so I tried to extend this range to start from
> 0xF0000000, or from 0xD0000000 the allocation works fine, but I am unable to
> access devices in the extended range
> 
> Anybody has idea why I am unable to use the complete 3G - 4G address range ?
> Is it related to some ACPI boot configuration that need to be changed, I can
> see in my dmesg
> 
> pci_root PNP0A08:00: host bridge window [mem 0xf4000000-0xf7ffffff]
> pci_root PNP0A08:00: host bridge window [io 0x1000-0x7fff]
> pci_root PNP0A08:00: host bridge window [io 0x0000-0x03af]
> pci_root PNP0A08:00: host bridge window [io 0x03e0-0x0cf7]
> pci_root PNP0A08:00: host bridge window [io 0x0d00-0x0fff]
> pci_root PNP0A08:00: host bridge window [mem 0xfed00000-0xfed03fff]
> pci_root PNP0A08:00: host bridge window [mem 0xfed40000-0xfed44fff]
> pci_root PNP0A08:00: host bridge window [io 0x03b0-0x03bb]
> pci_root PNP0A08:00: host bridge window [io 0x03c0-0x03df]
> pci_root PNP0A08:00: host bridge window [mem 0x000a0000-0x000bffff]
> pci_root PNP0A08:01: host bridge window [mem 0xf8000000-0xfbffffff]
> pci_root PNP0A08:01: host bridge window [io 0x8000-0xffff]
> 
> Is there a reason for this limited range ? Is it processor dependant ?

Yes, you should use the resource range in host bridge window, or you won't
request resource success. PCI hostbridge retrieve the host bridge window
from ACPI _CRS method, if _CRS is not exist, PCI may use global resource
iomem_resource and ioport_resource as its hostbridge window.

BIOS is responsible for the _CRS resource range report.

BTW, you can append the pci=nocrs in command line and try again.


Thanks!
Yijing.


> 
> Thanks 
> 
> --
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 


-- 
Thanks!
Yijing

Re: PCIe IOMEM Resource Allocation

[Yijing Wang]

On 2014/7/24 15:30, John Fadel wrote:
> I already tried pci=nocrs and I have exactly the same behaviour ..
> 
> Is there any way to extend this range after linux is up ?
> How can I access _CRS method to extend this range ?
> Is there a way to force larger range during the boot of linux ?
> 

First you should guarantee the extend resource range is free in your system,
you can check this from cat /proc/iomem;
Then if you add the pci=nocrs and still fail to use the extend resource range,
this is not a OS problem, and maybe BIOS does not allow OS to use extend resource out of default hostbridge
window.

There is no other way to extend the _CRS from OS.

Thanks!
Yijing.


> 
> 
> 
> On Thu, Jul 24, 2014 at 9:14 AM, Yijing Wang <wangyijing@huawei.com <mailto:wangyijing@huawei.com>> wrote:
> 
>     On 2014/7/24 14:35, John wrote:
>     > Hi
>     > I am trying to write a PCIe linux device driver to handle PCIe switches and
>     > endpoints that show up after the Redhat 6.4 linux is already up and running.
>     >
>     > If I try to allocate the resources of the PCIe switches & endpoints between
>     > 0xF4000000 and 0xF47FFFFF everything works fine .. But this range is quite
>     > full with other devices, so I tried to extend this range to start from
>     > 0xF0000000, or from 0xD0000000 the allocation works fine, but I am unable to
>     > access devices in the extended range
>     >
>     > Anybody has idea why I am unable to use the complete 3G - 4G address range ?
>     > Is it related to some ACPI boot configuration that need to be changed, I can
>     > see in my dmesg
>     >
>     > pci_root PNP0A08:00: host bridge window [mem 0xf4000000-0xf7ffffff]
>     > pci_root PNP0A08:00: host bridge window [io 0x1000-0x7fff]
>     > pci_root PNP0A08:00: host bridge window [io 0x0000-0x03af]
>     > pci_root PNP0A08:00: host bridge window [io 0x03e0-0x0cf7]
>     > pci_root PNP0A08:00: host bridge window [io 0x0d00-0x0fff]
>     > pci_root PNP0A08:00: host bridge window [mem 0xfed00000-0xfed03fff]
>     > pci_root PNP0A08:00: host bridge window [mem 0xfed40000-0xfed44fff]
>     > pci_root PNP0A08:00: host bridge window [io 0x03b0-0x03bb]
>     > pci_root PNP0A08:00: host bridge window [io 0x03c0-0x03df]
>     > pci_root PNP0A08:00: host bridge window [mem 0x000a0000-0x000bffff]
>     > pci_root PNP0A08:01: host bridge window [mem 0xf8000000-0xfbffffff]
>     > pci_root PNP0A08:01: host bridge window [io 0x8000-0xffff]
>     >
>     > Is there a reason for this limited range ? Is it processor dependant ?
> 
>     Yes, you should use the resource range in host bridge window, or you won't
>     request resource success. PCI hostbridge retrieve the host bridge window
>     from ACPI _CRS method, if _CRS is not exist, PCI may use global resource
>     iomem_resource and ioport_resource as its hostbridge window.
> 
>     BIOS is responsible for the _CRS resource range report.
> 
>     BTW, you can append the pci=nocrs in command line and try again.
> 
> 
>     Thanks!
>     Yijing.
> 
> 
>     >
>     > Thanks
>     >
>     > --
>     > To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>     > the body of a message to majordomo@vger.kernel.org <mailto:majordomo@vger.kernel.org>
>     > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>     >
>     >
> 
> 
>     --
>     Thanks!
>     Yijing
> 
> 


-- 
Thanks!
Yijing