-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hello,

> on my Ultra10 dmesg i have detected:
>
> machfb0 at pci1 dev 2 function 0: ATI Technologies 3D Rage I/II (rev. 
> 0x9a)
> machfb0: 16 MB aperture at 0xe1000000, 4 KB registers at 0x00000000
>
> the video card is detected as having 16Mb.

No, it's not. The aperture size is 16MB, as on most mach64 chips. This 
has little to do with video RAM size.

> But /var/log/XFree86.0.log shows only 8MB:
>
> (II) ATI(0): Using 8 MB linear aperture at 0xE1800000.

Just read the rest of machfb's output and the rest of XFree's log.
It's very likely that you have only 2MB video RAM.
Again, the aperture size is the address range used by the graphics chip 
which doesn't have much to do with video RAM size. All mach64 chips for 
instance map two views of the framebuffer and registers - one with 
endianness translation, one without - in their 16MB apertures.

> despite in my XF86Config trying:
> VideoRam    16384
>
> Any ideas on how to get all the ram recognised?

Since you don't have more RAM that's rather pointless.

> The graphics is suffering.

What exactly do you mean by that? Slower than modern graphics boards? 
Of course, it's 90s technology.

have fun
Michael
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (Darwin)

iQEVAwUBRMmlv8pnzkX8Yg2nAQIj2gf9EAaIEsZpQ8AdYJNvoR8eOi/MReiPha14
0TUbdaSMUqVvu2OGW8XkGpk+S+BtWDHsGqdjF/zaLbNTkYsBIFBvAYIGxBTRBiTo
dXJPDFlUZDv4qa4f7k8RsY9O+uBwXGY99hLsP/pdRaDLBWGtzvtr/PVUE0yNuBU1
AalDsCfK5O5/7d3A71TyxMeLIOH3rgwzpG0kmOEbLeULxS8caGAyCAfhZKIUHffQ
QY2lCPNK5NJXH8ozcywwNwl8j7Xed/xjM5aUHmvFZixuoL686LDq/Kp76DP9zZQd
VU+8zB5Mmv9FmkiZBtuUivq6xOFw+IhxqSCd3/rFRRXBAlVEVM0J+A==
=age9
-----END PGP SIGNATURE-----