Thank you for clarifying! > > > My Linux desktop get the IGD [..] Why not make more use of IGD > > > assignment in your configuration. > > > > Does a host system even boot with all graphics devices stubed? So am I > > right to assuming that x86 "graphic needs" are satisfied for POST but > > after that doesn't care what happens to the graphics devices > > afterwards? I don't mind a headless host at all, it will change > > somewhat how I setup things for crypto/storage but that I can solve. > > Linux doesn't require a graphics head, I use a serial console for my > system. I personally don't like entirely headless configurations (ie. > no graphical or serial console), but to each their own.
Well I like graphical output too, but for getting this to work I wouldn't mind missing it. For debugging I can always change in GRUB and start the host with a display or ssh into the host from a laptop. In the end I hope that a minimal host should run smoothly enough. > > > Concerns with your hardware choice otherwise: a) No ACS, you won't > > > be able to assign cards in CPU root port slots to separate VMs (see > > > vfio.blogspot.com), b) insufficient cores, how much are you willing > > > to have your storage server interfere with your gaming performance? > > > > a) Ok, I found your article > > http://vfio.blogspot.de/2015/10/intel-processors-with-acs-support.html > > these are the only choices? > > At the time of writing, I think it was fairly comprehensive, since > Intels product SKU marketing scramble with "Scalable Processors" I'm not > sure we've figured out the new decoder ring yet. Thank you for the blog articles. I'm still reading and it does clarify a lot, where I was confused before! > 6-cores? At best you can get 4-cores + threads on Intel processors with > IGD. Folks here tend to complain about every little micro jitter they > see in VM configurations and those can be difficult to eliminate > entirely without cores that can be dedicated to the gaming VM. You are right, I misread in my sea of browser tabs. Also misread the prices for a i7-6800k too, ~375 Euro that I can afford :) For the mainboard the Gigabyte GA-X99-UD4 has enough sata and usb3 for my storage/backup needs. From the manual I gather that it supports VT-d but I struggle to find a system block diagram to verify PCIE root ports to the pch and socket. http://www.gigabyte.us/Motherboard/GA-X99-UD4-rev-10#support-manual > The ACS override patch is unsupported and not destined for upstream, so > I would certainly not use it. ACS is typically included in the register > definition in the vol2 Intel datasheet. For AMD, good luck, we rely on > user reports due to lack of published specs. We know that AGESA 1.0.0.6 > is required for Ryzen root port ACS and I see on another list that > 1.0.0.7 is claimed will enable ACS on downstream switch ports for an > internal switch in X370. If we can get to the bottom of the NPT > performance issue, Ryzen may yet shape up to be a good device assignment > platform, but it's taking its time to get there. Thanks, Ohh, so, Ryzen does have ACS but "starter" problems. I guess as a VM beginner/novice I'm better off sticking to older hardware like i7-6800k and GA-x99-UD4 and try to get my setup running. Thanks and regards, Almer On 17 July 2017 at 18:47, Alex Williamson <alex.william...@redhat.com> wrote: > On Sun, 16 Jul 2017 12:59:16 +0200 > almer <almer...@gmail.com> wrote: > > > > Yes, it's possible, not even hard. > > > > Ok, so this isn't a hazy unattainable dream, perfect! > > > > > > > unbind cards or unload the module and RX 480 > > > > The host would get the IGP from the CPU. Both PCIE cards would be > > vfio-stubed, so as far as I understand it these cards will be handled by > > the vfio module in the host kernel and should be freely assignable to > > guests. Therefore don't use any power if no guest is using it. > > Um, not quite. Unless you have hotplug capable slots with independent > power control, the best we can do is put devices into a "low power", D3 > power state. The PCI spec requires devices to support this state, but > does not require devices to meet any particular standards for power > consumption in this state. I would characterize D3 as slightly better > than doing nothing, no more. In fact, the power consumption might be > lower with the VM running and the guest driver managing the device > specific power controls. > > > I'm not deadset on Nvidia I rather would use something else because of > the > > uncertainty that comes with and Nvidia driver. My guess is that their > > proprietary Nvidia linux driver would have VM detection too, but didn't > > find confirmation on this. I would like to use a AMD graphics card just > to > > be safe and out of that armsrace, AMDs driver doesn't block like Nvidia > > does. > > But I got discouraged by AMD graphics card PCIE reset issue reports and I > > couldn't make heads and tails about it. If any RX 480 works, great. I > will > > have to look more into this. > > > > > > > My Linux desktop get the IGD [..] Why not make more use of IGD > assignment > > > in your configuration. > > > > Does a host system even boot with all graphics devices stubed? So am I > > right to assuming that x86 "graphic needs" are satisfied for POST but > after > > that doesn't care what happens to the graphics devices afterwards? I > don't > > mind a headless host at all, it will change somewhat how I setup things > for > > crypto/storage but that I can solve. > > Linux doesn't require a graphics head, I use a serial console for my > system. I personally don't like entirely headless configurations (ie. > no graphical or serial console), but to each their own. > > > For the IGP to be stubed and passed through I need a ACS capable CPU? As > it > > seems I wrongfully assumed that Vt-d and Vt-x support entailed this. > > IGD is not dependent on ACS, IGD is a single function device connected > directly to the PCIe root complex. It will always be in an IOMMU group > of its own. Unfortunately the Intel systems that include proper ACS do > not include IGD, and conversely, if you have IGD you do not have ACS. > Plan your usage accordingly. > > > > Concerns with your hardware choice otherwise: a) No ACS, you won't be > > able > > > to assign cards in CPU root port slots to separate VMs > > > (see vfio.blogspot.com), b) insufficient cores, how much are you > > > willing to have your storage server interfere with your gaming > > performance? > > > > a) Ok, I found your article http://vfio.blogspot.de/2015/ > > 10/intel-processors-with-acs-support.html these are the only choices? > > At the time of writing, I think it was fairly comprehensive, since > Intels product SKU marketing scramble with "Scalable Processors" I'm > not sure we've figured out the new decoder ring yet. > > > Doesn't AMD support this too? AMD CPUs are usually weaker in single core > > performance, so I ignored AMD CPUs for years. But seeing the prices I > > wonder if they have an alternative for ~450 Euro price range. Some of the > > Intel CPUs you listed are way out of my budget. The strongest and > somewhat > > affordable listed is a i7-6850k. AMD ryzen 1800x costs ~470 Euro, but > > doesn't have an IGP and I didn't look into AMD CPUs at all so I don't > know > > if they support ACS it has AMD-V tho. > > Previous generation, 990-based AM3/+ sockets supported ACS. Ryzen > systems seem to have implemented it in hardware, but nobody told the > BIOS team that it was important to enable and support for ACS is slowly > being added. Specifications are hard to come by for AMD chips though, > so we only have user reports to tell us how various systems fair. > Increased core count in Ryzen is certainly desirable for virtualization > scenarios, but the number of PCIe lanes from the processor can lead to > limited I/O options or additional switch components that may ruin the > ACS provided by the root ports. Note that there's also an assigned GPU > performance issue with AMD's NPT as well that isn't understood. > > > b) Well. I'm used to Intel quad core CPUs. Seeing that no matter what I > buy > > I will endup with 6 cores at least, I guess I can live with it. Desktop > > guest and host heavyload-PIDs will get taskset to one core and the gaming > > guest gets the rest pinned and taskset. So my guess is that any > > crypt/storage/desktop spike shouldn't be noticed in the gaming guest. > > 6-cores? At best you can get 4-cores + threads on Intel processors > with IGD. Folks here tend to complain about every little micro jitter > they see in VM configurations and those can be difficult to eliminate > entirely without cores that can be dedicated to the gaming VM. > > > > The only major issue is that running things involving sound and video > > becomes > > > not possible on such desktop. But those can be viewed/listened > locally, on > > > whatever actual machine you happen to be at. (Or also there are ways to > > pass > > > through sound from a remote desktop, or use video-efficient protocols > > such as > > > SPICE, but for my use I did not look into those as of yet). > > > > This would be an issue. I didn't look into audio and microphone that > much. > > I would like to hear the audio from desktop guest and gaming guest and > have > > microphone available at least in the gaming guest for voice chat. Right > now > > this doesn't matter that much. Host and guests will be all GNU/Linux > > distributions so without having looked into it further I guess there is a > > server solution if any audio/mic passthrough scenario wouldn't work. I > > guess your SPICE suggestion is such a solution. > > Monitor wise I initially thought about HDMI switching host and desktop > > guest, but as it seems that I can vfio-stub all graphics devices with a > > proper CPU, I won't need the passive PCIE card in the case of i7-6850k > > anymore and can use the IGP for the desktop guest instead. The desktop > > guest will be dual monitor setup and the gaming guest will be switched on > > one of the monitors, like I have it right now with separate computers. > > Keyboard + mouse, I already use a two port usb switch. I guess I can > still > > use that to switch between desktop and gaming guests, after one of the > two > > usb-switch cables is passed through to the desktop guest after boot. > > > > I'm exited and a bit confused. > > > > How do you see if a CPU does support proper isolation or not? It isn't > the > > feature list like AMD-V or Vt-d/x only. Is it a combination of mainboard > > chipset and CPU? I ask because I see the TDP wattage difference between > > ryzen 7 1800x and the i7-6850k. So being relatively equal in price and > > performance I tend towards the ryzen CPU. In the last couple hours I fail > > to find if it would support proper PCIE isolation or not. In the search > > stumbled upon ACS kernel patch, if possible I don't want to apply the ACS > > patch to the host kernel. > > The ACS override patch is unsupported and not destined for upstream, so > I would certainly not use it. ACS is typically included in the > register definition in the vol2 Intel datasheet. For AMD, good luck, > we rely on user reports due to lack of published specs. We know > that AGESA 1.0.0.6 is required for Ryzen root port ACS and I see > on another list that 1.0.0.7 is claimed will enable ACS on downstream > switch ports for an internal switch in X370. If we can get to the > bottom of the NPT performance issue, Ryzen may yet shape up to be a > good device assignment platform, but it's taking its time to get > there. Thanks, > > Alex >
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