ATI Catalyst VRAM size detecting problem.

[gerijani]

Hi volks,

I have a strage problem. Well, actually as I saw a lot of people have one like this.

Situation:
I have an Asus EAH 4850 with 512MB DDR3 RAM. As I checked it on my Fedora 10, I saw that the system doesn't mapped all the VRAM:

[root@destiny ~]# lspci -v -s 05:00.0
05:00.0 VGA compatible controller: ATI Technologies Inc RV770 [Radeon HD 4850] (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Device 026a
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at d0000000 (64-bit, prefetchable) [size=256M]
Memory at fbee0000 (64-bit, non-prefetchable) [size=64K]
I/O ports at e000 [size=256]
Expansion ROM at fbec0000 [disabled] [size=128K]
Capabilities: [50] Power Management version 3
Capabilities: [58] Express Legacy Endpoint, MSI 00
Capabilities: [a0] Message Signalled Interrupts: Mask- 64bit+ Count=1/1 Enable-
Capabilities: [100] Vendor Specific Information <?>
Kernel driver in use: fglrx_pci
Kernel modules: fglrx

The kernel module is compied from the original ATI radeon driver "ati-driver-installer-9-10-x86.x86_64.run". I found people with the same problem on Ubuntu. So I think this isn't a kernel or distribution problem instead of a driver.

Have anyone a suggestion?

[FiggyG]

My 512MB 3850 has the same ouput, yet the fglrx control panel states 512MB. I haven't looked into it any further.

[gerijani]

Lucky...I guess. My control center sad even worst: only 128MB. Something is really buggy. What distro and ati-catalyst do you use? Kernel is distro-version (patched) or clean?

Here is mine:

Fedora 10 with kernel 2.6.29.6-99.fc10.x86_64 SMP
ati-driver-installer-9-10-x86.x86_64


By the way, stange is that in X log I see the right size:

(--) fglrx(0): Video RAM: 524288 kByte, Type: GDDR3

But this doesn't calm me. As I know system use what it mapped. And that's what lspci shows. I still don't understand this so I think, I will compile my kernel again and see what happen.

[mlau]

Originally Posted by gerijani

Memory at d0000000 (64-bit, prefetchable) [size=256M]

This just states that the aperture into the VRAM is 256MB in size after BIOS
has assigned resources. The kernel can of course change this (if it finds enough
free contiguous virtual space) and I believe modern GPUs have MMU's which
allow them to map various parts of the vram into this aperture (so the whole
256MB window won't map 1:1 to physical vram).

Don't worry about it, the drivers usually know their hardware and what to do.