I'm currently using Ubuntu 12.04 64bit. After installing ATI/AMD proprietary FGLRX graphics drivers via Additional Drivers, I checked the status of my VGA card using lspci -v. Here's the output:

02:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI M96 [Mobility Radeon HD 4650] (prog-if 00 [VGA controller])

Subsystem: Dell Device 0456     
Flags: bus master, fast devsel, latency    0, IRQ 46    
Memory at d0000000 (32-bit, prefetchable)    [size=256M]    
I/O ports at 2000 [size=256]    
Memory at cfef0000    (32-bit, non-prefetchable) [size=64K]     
[virtual] Expansion ROM at cfe00000 [disabled] [size=128K]  
Kernel driver in use: fglrx_pci     
Kernel modules: fglrx, radeon

As mentioned in the title, my VGA card is 1GB and yet my computer only recognizes 256MB. My question is: "How to make my computer fully recognize the capacity of my ATI Mobility Radeon HD 4650 (1GB)?"

  • @basharat-sial, thank you very much for editing my post. :D
    – Thi An
    Apr 29, 2012 at 6:08

1 Answer 1


See this forum thread on phoronix: http://phoronix.com/forums/showthread.php?26231-r600-uses-only-256-mb-video-ram

The 256M you see there is actually called the BAR limit. It's the amount of memory the cpu can map: "The BAR limit (aperture visible to the CPU) is 256 MB but the latest memory manager code can let the CPU access more than 256 MB by dynamically mapping it into the aperture. The GPU can always address the entire video memory anyways. I believe the 256MB limit is a PCI spec."

On my ati card typing the following gives me an accurate reading:

 grep kB /var/log/Xorg.0.log

which outputs

 [    24.091] (II) fglrx(0): VESA VBE Total Mem: 16384 kB
 [    24.123] (--) fglrx(0): Video RAM: 1048576 kByte, Type: DDR3

The second line denotes my 1GB of video memory, while lscpi -v gives me 256 like you. I got this command from this comment.


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