Reduce Max TOLUD to 1G or increase memory allocated for PCIe End Point

[k3nway]

Dear Intel Support,

I have a module which is using Intel Atom® x5-E3940 and I would like to reduce maximum TOLUD to 1G. In the BIOS, I have implement custom settings to reduce TOLUD to 1G by adjusting the memory ceiling value. Based on BIOS debug log, BIOS successfully changed the memory ceiling value but when I boot into Linux and check the memory allocation with iomem, it is reverted back to 2G. 

The main reason I would like to reduce maximum TOLUD is to increase memory available for PCIe end point.

My module have 8GB memory, and I noticed that BIOS allocated PCIe memory on in 32bit addressing range. It is still the same after enable "Advanced > PCI Subsystem Settings > Above 4G Decoding". 

Can you advise on this?

Thanks and regards,

Kenway

[Diego_INTEL]

Hello @k3nway,

Thank you for contacting Intel Embedded Community.

Just to let you know, Apollo Lake is not actively supported anymore.

https://www.intel.com/content/www/us/en/support/articles/000022396/processors.html

I checked internally and it seems that the TOLUD is being set as default at 2 GB in the SIC code, so I think it needs a modification there but I don't see that has been validated.

Best regards,

@Diego_INTEL 

[k3nway]

Hi @Diego_INTEL ,

Can you share with me how I should modify the SIC code in order to reduce the TOLUD? I would like to reduce TOLUD to 1GB.

Thanks and regards,

Kenway

[Diego_INTEL]

Hello @k3nway,

Maybe you can try to ask to your BIOS vendor in this regard, but we don't modify and share anything from SIC, I just know that TOLUD is set to 2 GB.

Best regards,

@Diego_INTEL