PCi Memory Resource allocation in Kernel

diya26 · 07-09-2015, 02:33 AM

Hi,

I am working on pcie switch 8749. I have 4 endpoint devices each requesting 8MB memory space. But kernel allocated 1MB to each endpoints.

Why memory allocates 1MB space and how to tel kernel to allocate request memory size.

Please guide,

Keruskerfuerst · 07-09-2015, 03:10 AM

Did you try to search in google with "pcie memory allocation"?
http://vger.kernel.org/

diya26 · 07-09-2015, 05:45 AM

Yes of course but could not get enough information from Google.

Bios is allocating total 64MB for PCI space. There are many endpoint devices connected to switch. For one of endpoint i am requesting to allocate 8Mb but pci allocates 1MB default.

As far i guess, pci will automatically allocate the bar address and size on request.

But in my case, it is not allocating.

Should i need to see anything in BIOS.

Keruskerfuerst · 07-09-2015, 02:06 PM

You can also ask the kernel developers.

diya26 · 07-21-2015, 12:33 AM

Hi,

Thanks for reply,

I am able to sort out the issue.

The problem was in endpoint pci space. The address bar was not correctly masked to get the required memory space.Once this was handled , i am able to view 8MB space allocated to endpoint
in Bios