VIA driver: VideoRAM option

[Gregoire Gentil]

Hello,

I would like to change the Video Ram size on my Linux-Ubuntu
configuration. But whatever I put in VideoRAM of the xorg.conf file, the
video ram amount doesn't change and the report in /var/log/Xorg.0.log is
always the same:
(--) VIA(0): videoram = 4096k

I'm running:
Xserver-xorg-core		1.0.2-0ubuntu9
xserver-xorg-driver-via	0.1.33.2-0ubuntu4

Extract of /etc/X11/xorg.conf:
Section "Device"
	Identifier	"Via Teechnologies, Inc. VT8623 [Apollo CLE266]
integrated CastleRock graphics"
	Driver 	"via"
	BusID		"PCI:1:0:0"
	VideoRAM	8192
EndSection

What should I do to put more video ram? I don't think that I have any
BIOS limitation. My final objective is to run in 1280x1024 32 bit and
the log file indicates that there is not enough video ram. It's the
reason why I'm trying to play with the VideoRAM option.

Thanks by advance,

Gregoire