Thinkpads Forum

These claims make perfect sense and in fact have been known and verified for a long time.

The only reason you cannot utilize the full 4GB is the MMIO space for PCI/PCIe devices. If you are willing to sacrifice these devices, you can free more of the address space for memory. But there are some things you cannot go without (graphics, ATA controller), and as mentioned, there are alignment requirements.

For practical purposes, if you want to keep the system usable and useful (with USB, networking, etc.), you are unlikely to get anything over 3.5GB addressable RAM. Not that I did the math, but I see no point in it. A few hundred megs here or there would not make any difference.

Regardless of the firmware (Lenovo BIOS vs Coreboot), the root of the issue is the 32-bit address space of the 945 chipset.

Coreboot only has an advantage because it allows you to free up some RAM by disabling certain devices.

But trading functionality for usable RAM might not sit well with users who want to "max out" their T60s.

Coreboot sounds more interesting on the X60, where Expresscard and discrete graphics are nonexistent. With 224MB shared video RAM + 128MB for Cardbus, you're looking at a little over 3.7GB max.

axur-delmeria wrote:Coreboot sounds more interesting on the X60, where Expresscard and discrete graphics are nonexistent. With 224MB shared video RAM + 128MB for Cardbus, you're looking at a little over 3.7GB max.

Well, you'll still need space for other devices - Ethernet, WiFi, USB Controller, ATA Controller. Does CardBus alone really take a full 128MB chunk? Plus there are alignment requirement which I am not sure about. Some devices may not need much space, but due to alignment requirements may block out a bigger block...

So if I disable certain devices like cardbus, Wifi which I don't need anyway, I can get more usable memory out for programs?

ThinkMac2003 wrote:So if I disable certain devices like cardbus, Wifi which I don't need anyway, I can get more usable memory out for programs?

Not with the existing BIOS.

You need to install Coreboot for something like that.

It's fascinating to read all these.

Where can I get Coreboot and steps to install it?

Why would you want to? For the sake of experiment?

See libreboot.org/docs/hcl/index.html#supported_list and www.coreboot.org for further information. Be prepared for the unexpected, though.