Question about Ram and restricted drivers

I am currently Running Ubuntu Hardy and I added 2 more gb’s ram to make it a total of 4 gbs ram when I did this it made it so that I couldnot boot to desktop with the fglrx restricted driver I had to use the mesa driver or use the livecd to get to desktop, I posted on the LQ website and had allot of people telling me different thiungs to do but none of them worked and I also posted on the Ubuntu site and I had one reply that made total sense

When you use the LiveCD it probably uses different video drivers than you’ve got installed.

What most likely causes this is the video card needing to allocate a large range of PCI IOMEM but, because you’ve got 4GB of RAM installed, there is not enough free IOMEM address space below the 4GB boundary for the PCI IOMEM window - video devices usually need 256MB or 512MB.

When the PC only has 2GB of RAM, there’s a window of 1.25GB available for PCI IOMEM. With 4GB of RAM, 1GB is mapped above the 4GB boundary, leaving just 256MB of PCI IOMEM space between the 3GB and 4GB boundaries.

As all PCI devices in the system have to share this space, and the video device isn’t the first to request an IOMEM allocation, the system doesn’t have enough IOMEM space and the video device doesn’t get any.

That means it will only operate in text and low-resolution graphics modes. When a high-resolution mode is attempted it can’t do it, and fails the way you describe.

There isn’t a solution at present. I’m currently putting the finishing touches to new Linux kernel PCI IOMEM allocation system that works as well as, if not better than, Windows. That won’t appear in mainline for a few months though, and I doubt it’ll get backported to existing releases.


After reading this post I have made the dicession to try a distro that will be able to handle 4gigs of ram and also handle the driver so I can occasionally play online fps games will I have the same problem if I install opensuse?

I know that I had a machine with 4 GB of RAM on opensuse 10.3 and also used the fglrx driver with no problems. But I did install the 64bit version which may have not had the same problem. You could try that if the processor and motherboard supports 64bit.

Thank you for reply, I have actually installed openSUSE and I have to say that it seems to work perfectly there just a bit of a learning curve coming from Ubuntu but that’s not a real problem

Linux-Kernel Archive: Re: PCI: iomem bigger than 4GB

As far as I understand this was fixed as of kernel 2.6.20.x