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Dell FX160: Linux 

Linux

I ran Tiny Core Linux 7.2 from a USB drive without any problems.

Later on I had no issues with the 32-bit and 64-bit versions of Tiny Core 12.0 (but see below)

3GB RAM Limit

In March 2023 I heard from Björn. As far as we can see, with 4GB of RAM fitted, what ever OS you use you only have 3GB of RAM available. This is to be expected with a 32-bit OS where you generally lose ~1GB to the 'PCI hole' and the shared video memory. With a 64-bit OS the memory overlaid by the memory mapped PCI I/O address space can effectively be moved to above the 4GB 32-bit address limit where it can be used by applications. All you should lose is the memory taken for the video buffer. As noted above this does not happen with the FX160.

I do not know the exact reason for this. The Intel Atom processor (230 in my case, 330 for Björn) was a cheap CPU aimed at the nettop market. As far as I can see there are a number of explanations here:

  1. The Atom CPU and/or chipset can't address memory above 4GB.
  2. The physical implementation doesn't support memory addresses above 4GB.
  3. There is bug in the BIOS.

Björn tried out a variety of BIOSs but no avail.

If you search the Internet, on laptop forums you'll find complaints about some Lenovo and Dell laptops which suffer from the same problem - 1GB of missing memory when using a 64-bit OS. These all used the Intel 945GM chipset - not used here in the FX160 but maybe we have the same sort of behaviour in the SiS chipset?

This is an excerpt from section 9.2 of mobile-945-express-chipset-datasheet:

"The Memory Controller Hubs provides a maximum DRAM address decode space of 4 GB. The MCH does not remap APIC or PCI Express memory space. This means that as the amount of physical memory populated in the system reaches 4GB, there will be physical memory that exists yet is non-addressable and therefore unusable by the system."

i.e. As it can't remap MMIO (Memory Mapped IO) space that 1GB of RAM is lost.

I did track down an SiS 'Product Info' data sheet on the SiSM671. This included the not particularly helpful statement:

Single Channel Memory Controller
  • Supports DDR2-667/533/400
  • Supports two DIMMs
  • Up to 2GB per DIMM with maximum memory size up to 4GB

 


Any comments? email me. Added November 2016    Last update March 2023