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#1 2017-05-24 20:50:14

dviktor
Member
From: Moscow
Registered: 2015-10-18
Posts: 155

[SOLVED] Arch and Intel DVMT

Hello! I have Asus VivoMini VC65 nettop with Intel Core i3-6100T CPU on board. It have Intel HD Graphics 530 integrated GPU. In my UEFI I have no editable settings for dedicated GPU RAM (latest firmware). In lspci I have:

[viktor@desolve-nettop ~]$ lspci -v -s 00:02.0
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06) (prog-if 00 [VGA controller])
	Subsystem: Intel Corporation HD Graphics 530
	Flags: bus master, fast devsel, latency 0, IRQ 125
	Memory at de000000 (64-bit, non-prefetchable) [size=16M]
	Memory at c0000000 (64-bit, prefetchable) [size=256M]
	I/O ports at f000 [size=64]
	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: <access denied>
	Kernel driver in use: i915
	Kernel modules: i915

while in dmesg I see:

[viktor@desolve-nettop ~]$ sudo dmesg | grep drm
[    0.705255] [drm] Memory usable by graphics device = 4096M
[    0.705257] fb: switching to inteldrmfb from EFI VGA
[    0.705363] [drm] Replacing VGA console driver
[    0.711543] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    0.711544] [drm] Driver supports precise vblank timestamp query.
[    0.718594] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_26.bin (v1.26)
[    0.719838] [drm] GuC firmware load skipped
[    0.720305] [drm] Initialized i915 1.6.0 20170123 for 0000:00:02.0 on minor 0
[    0.722654] [drm] Initialized i915 1.6.0 20170123 for 0000:00:02.0 on minor 0
[    0.764336] fbcon: inteldrmfb (fb0) is primary device
[    0.851473] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
[    2.346105] [drm] RC6 on
[21034.284297]  i8042 serio i915 video button i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm intel_agp intel_gtt

So, theoretically my IGPU can use up to 4 Gb of my RAM (8 GB total on board), but lspci says that only 256 Mb is available. VideoRam option in xorg.conf for intel driver seems to be deprecated. So I wonder if there any ways to increase dedicated GPU RAM or directly use Intel DVMT? As for now it seems like DVMT is not working - when I launch some graphics-heavy application (e. g. Bioshock Infinite @ steam) I see the same 256 Mb of dedicated GPU RAM in lspci output.

Is there any ways to increase dedicated GPU RAM at kernel or xorg level? Or can I enable Intel DVMT not using UEFI?

Thank you

Last edited by dviktor (2017-05-25 12:55:39)

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#2 2017-05-24 21:31:11

R00KIE
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From: Between a computer and a chair
Registered: 2008-09-14
Posts: 4,734

Re: [SOLVED] Arch and Intel DVMT

Trust what dmesg says, what you see on the output of lspci (if I'm not wrong) is the amount of video memory the cpu can access directly.


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#3 2017-05-24 22:27:08

tom.ty89
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Registered: 2012-11-15
Posts: 896

Re: [SOLVED] Arch and Intel DVMT

IIRC, in Linux intel gfx does not work the same as it does in Windows for the video memory part. The memory reserved by the BIOS/UEFI will not be used at all, and instead i915 (intel gfx kernel driver) would have some sort of direct access to the system memory, and up to 2GB can be used as video memory. I don't remember if that's hard-coded or can be adjustable via sysfs or so though.

However I don't really have any source document on hand, so just take it as a hearsay and do further research if desired.

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#4 2017-05-25 09:16:46

dviktor
Member
From: Moscow
Registered: 2015-10-18
Posts: 155

Re: [SOLVED] Arch and Intel DVMT

Thank you for your answers.
But what I want to mention: hardware video decoding in VLC via VAAPI works great, old games such as Quake III Arena, Half-Life 1 are also have 60 fps at maximum video settings, but new games (if we can name Bioshock Infinite as "new") are extremely choppy even on minimum video settings (about 20 fps) so I thought that there no enough video RAM for Intel GPU
Also somewhere in product specifications I've seen that these GPU can use only up to 1.7 Gb of installed RAM. So I doubt in values that dmesg' output contains

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#5 2017-05-25 12:14:18

R00KIE
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From: Between a computer and a chair
Registered: 2008-09-14
Posts: 4,734

Re: [SOLVED] Arch and Intel DVMT

Intel's page[1] says the gpu should be able to access up to 64GB, but I suppose specific board implementations could limit that (just speculating).

You can't expect an integrated GPU to run demanding games at the same speed as a discrete card of the same vintage, I'd say that 20fps is already good. You have to remember that the gpu is using the system's ram, which is slower than the dedicated vram in discrete cards.

Now if you had an iris or iris pro gpu that would be a different matter. Those are starting to get interesting and I'm curious to see what intel gpus can do tow or three generations from now. That said, I do have an HD Graphics 520 and I'm quite happy with it, but I don't really play games (but I did test a few just out of curiosity about the speeds I would get and to check everything was working as intended).

[1] http://ark.intel.com/products/90734/Int … e-3_20-GHz


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#6 2017-05-25 12:14:30

tom.ty89
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Registered: 2012-11-15
Posts: 896

Re: [SOLVED] Arch and Intel DVMT

Oh I actually missed the fact that you already found the relevant message in dmesg. So yeah I guess it's not 2GB but maybe it's like 50% of your total RAM or so that would be accessible via the i915 driver, while the 256M you see in lspci is the one reserved via the BIOS/UEFI (which will almost nost be used at all; if the BIOS/UEFI has an option in its setting, it's probably best to adjust it to the minimum possible value to avoid wasted RAM).

As for the number that is listed in the prod. spec., I am not sure what exactly it refers to. It might be true that the 4GB is only the soft upper limit of the driver, where there's a hardware limit in the iGPU as well (which would be the bottleneck). But honestly I don't really know how it works (across different OSes).

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#7 2017-05-25 12:55:25

dviktor
Member
From: Moscow
Registered: 2015-10-18
Posts: 155

Re: [SOLVED] Arch and Intel DVMT

Thank you all for explanation! Things became really clear now smile

Last edited by dviktor (2017-05-25 12:56:05)

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