Bug#493521: xserver-xorg: can only use half of my video RAM

[Brice Goglin <Brice.Goglin@ens-lyon.org>]

Zack Weinberg wrote:
> (II) RADEON(0): Generation 2 PCI interface, using max accessible memory
> (II) RADEON(0): Detected total video RAM=524288K, accessible=262144K
> (PCI BAR=262144K)
> (--) RADEON(0): Mapped VideoRAM: 262144 kByte (256 bit DDR SDRAM)
>   

I am reading this as:
* the driver rea somewhere in the registers that the board has 512MB
* the PCI config space only makes 256 available through I/O MEM

It could mean that the board keeps 256MB available for its own use
(internal memory management, or DMA from/to the host) but the host
cannot write/read directly in there.

Brice