I've been doing a lot of buying and selling of my Mac equipment lately in order to get some more recent stuff, and my most recent purchase was a 27" late 2015 iMac, which I got by trading in an older one. This computer is really different though, because of its 5K resolution (5120x2880). I hadn't realized at the time that this might cause problems with Linux distros, but it does. I wanted to run Ubuntu 17.04 on it, but no dice - neither an existing installation or a live installation disk would boot. I would always end up with a dark purple screen. I searched for solutions and came up with a few posts suggesting a change to the grub boot parameters (adding nointremap or nomodeset or acpi=off) would fix this, but it didn't. I tried Ubuntu 16.04 and got the same result, so I then tried some other distros as well as the Ubuntu 17.10 beta 2. The latest Fedora wouldn't boot at all, nor would Elementary. Clonezilla would boot to the first screen and then freeze. Ubuntu 17.10 beta and OpenSuse Leap would boot, but they would take 5 minutes to do so. I didn't try installing OpenSuse, but I did Ubuntu. It did install, and changing its grub boot parameter would allow it to boot up, but again taking many minutes. When it did boot up, network-manager would not connect to the internet with either ethernet or wifi.
I don't know if it matters, but this iMac is the mid-level one with the 3.3 ghz i5 and a Radeon R9 M395 video card; maybe that particular video card is more problematic than the default. At this point I was ready to tear my hair out, but I tried one more distro: Linux Mint Cinnamon 18.2. Changing the boot parameter to nointremap, it booted right up, installed OK, and the installation booted up normally once I permanently added nointremap to the boot sequence! I haven't been interested in either Linux Mint or the Cinnamon desktop for a long time, but I figured I'd better make this to my liking if it's the only thing that would work properly. I spent a lot of time customizing it to my liking, which basically means changing icons and making the panel look like Ubuntu Unity. Turns out that you can do this by adding a vertical bar on the left side of the monitor and pinning my most used applications to it. I can live with this! My only complaint is the lack of fine-grain magnification adjustment in Cinnamon; the only choices are default or 2x magnification for high dpi. (Ubuntu allows you to magnify to tenths.) But the 2x works for me.
Even though I'm happy with Mint, I'm still bugged about not being able to install Ubuntu. Others have been able to get Ubuntu to boot on a 5k iMac, so why couldn't I (unless it's the specific video card)? Mint 18.2 is a derivative of Ubuntu 16.04, so why should it boot so easily when 16.04 wouldn't boot at all? What is different about 17.10 beta that it can boot (though with a lot of stalling) when the previous version cannot? Also, I don't like the fact that I can't boot a Clonezilla disk on this because I use it a lot. I'm wondering what I can try to get Ubuntu and Clonezilla to boot from a live USB, and install in the case of Ubuntu. Might it work if I simply copied all of the grub boot parameters in Mint and use them with Ubuntu? I might try that next, but any suggestions would be welcome.
Probably not that helpful but there are Linux Radeon drivers you can download. With a resolution that high, default drivers probably won't cut it. You may have been lucky enough in Linux Mint that it picked up and installed an appropriate Radeon driver but I'm not sure.
Actually, I don't think Mint did because when I looked at drivers, it didn't register anything other than Intel Microcode. At any rate, assuming I found the appropriate one and downloaded it, how would I use it? Is this something I can deal with on the installer or something I have to add after a distro is installed? I'm not sure the latter would help since I can't even boot up a Ubuntu installer other than the 17.10 beta and the network wasn't functioning in the 17.10 beta.
Incidentally, even Mint doesn't give me the full resolution, though it did give me something halfway between 2560x1440 and full 5k resolution. This is a known problem with Linux on 5k and the resolution I get is quite good.
Quote from: fox on October 15, 2017, 05:58:21 PM
Actually, I don't think Mint did because when I looked at drivers, it didn't register anything other than Intel Microcode. At any rate, assuming I found the appropriate one and downloaded it, how would I use it? Is this something I can deal with on the installer or something I have to add after a distro is installed?
You'd have to add it after installation. If your network isn't working though, I doubt a video driver will be much use to you except that maybe it would help in troubleshooting your network problem.
I just did a quick search and found that there were Linux drivers for that card. They were just for Fedora, openSUSE and Ubuntu and older versions at that, but there were installation instructions with the download. I just searched "Radeon R9 M395 linux", I believe. Other than that, I know no more than you do.
I've made a bit of progress in getting Ubuntu to boot on my 5k iMac. Using Ubuntu 16.04, I can get it to boot right up when I use the grub parameters acpi=off and nomodeset. These parameters were actually recommended in one posting, but another suggested that nointremap would also boot and have none of the negative effects of acpi=off, so I hadn't tried that before. Unfortunately, while it does boot right up, window response is noticeably slow with these parameters; e.g., moving or expanding windows. Not something that I would be happy with. But at least I know now that a/the major reason for problems booting Ubuntu installers on the 5k iMac relates to acpi. I did try a few other alternative acpi options, but none except turning it off worked. But I don't really get why an acpi setting should relate to a 5k display, unless the problem is more the video card than the display. I wonder if I installed Ubuntu with the acpi=off setting and then added the proprietary Radeon driver if this would solve things. But what is Mint doing that's different because it works fine without the Radeon driver installed?
Speaking of Mint, dropping the default resolution to 2560x1440 does wonders for some of the windows. That's only half the resolution this iMac is capable of, but it's still darn good and I didn't buy that model specifically because of the 5k resolution. Maybe future distros will have kernels with native 5k capability.
More progress. I tried a bunch of acpi settings, and besides acpi=off, two other settings work in combination with nomodeset, though they still result in window effects. The two are:
acpi=noapic nomodeset
acpi=noapic acpi_backlight=vendor nomodeset
I tried both with a Ubuntu 17.04 installation on an SSD run externally. In both cases, boot-up was fast. In the first case, window movement was slow; you could see the delay effects when dragging or expanding a window. In the second case, window movement wasn't slow, but the animation when moving windows was lost. In other words, when you move or expand a window, you see only an outline until the action ceases; then the change shows instantly. But also in the second case, I lose the ability to change the screen brightness through "settings"; the setting to do so in "brightness and lock" is gone. I suspect that the missing brightness setting can be fixed with software. But I don't know the cure for the lose of real time window dragging effects. This is not a big deal, however, so I now have the possibility of installing Ubuntu on my 5k iMac. But since everything seems to be working in Mint, I'm probably going to stick with it now and continue to see how I can fix the window dragging in Ubuntu. Perhaps by installing the proprietary Radeon video card, as suggested by Jason?
It's certainly worth a try since what you're experiencing is definitely related to the driver. It may be that Mint is using an open source Radeon driver whereas 16.10 doesn't see it? Maybe they dropped support for it? System info in either distribution might tell you what driver you're using. Also thinking that Mint probably is still using X.org while the much newer Ubuntu 17.10 is probably using the newer display server (can't recall the name of it right now). So they very likely have at least a slightly different list of available drivers. But honestly, I haven't had to get into video idriver nards in a long time to fix anything but you might have to get optimal performance in Linux. Wish I could help more but I'm out of my league here :)
Jason, your messages are helpful nevertheless and I will look into the driver issue, though I am happy at the moment with using Mint. Incidentally, the newer display server is Wayland, and it might be relevant on Ubuntu 17.10 since it is the default. But Ubuntu 17.04 was still using Xorg.
I like the direction Jason's headed with this issue. My 11" netbook is AMD CPU- and video-based, and AMD drivers were the only thing that could properly address the video subsystem in the hybrid APU. Worse still, it took a two or three updates before the "this driver does not support the installed hardware"-type message in the lower right corner of the screen finally disappeared.
And the following update broke it again... Go figure. It seems fine now, but I may well have reverted back to a default Nouveau driver or something, since, not being a gamer and wanting every last ounce of processing speed out of the GPU segment of the processor, I'd rather have something stable than something blazingly fast.
And when is it *EVER* OK to have to work this hard for it?
I didn't thoroughly read all the replies here before posting, so apologies if this is a repeat. One of the issues you may be running into is that the computer has dual video. Either the stock distro may only be detecting the onboard Intel, or may be using the video out as your primary display through the second graphics card. It may help your queries if you include the dual video nature in your searches.
Thanks, Scott. I don't think this iMac has dual video. The video card is described as "AMD Radeon R9 M390 graphics processor with 2GB of GDDR5 memory" and there is no indication of a dual mode. It isn't hooked up to any external monitors, either. Interestingly enough, I just discovered that what is making Mint work is not only the distro and the boot parameters, but also the kernel. The default kernel is 4.8.0-53. I tried upgrading to 4.10.0.37, which is an option given in Mint's Update Manager. When I did so, it wouldn't boot, at least not with the same boot parameters as the older kernel. The text was giving me various errors in "brcmfmac". Go figure! If anything, I would think a newer kernel is better on a relatively new computer.
Now, you*know* that's a wifi error message, right, Mike?! <^8#
(Figures...)
Quote from: fox on October 30, 2017, 04:11:47 PM
Thanks, Scott. I don't think this iMac has dual video. The video card is described as "AMD Radeon R9 M390 graphics processor with 2GB of GDDR5 memory" and there is no indication of a dual mode. It isn't hooked up to any external monitors, either. Interestingly enough, I just discovered that what is making Mint work is not only the distro and the boot parameters, but also the kernel. The default kernel is 4.8.0-53. I tried upgrading to 4.10.0.37, which is an option given in Mint's Update Manager. When I did so, it wouldn't boot, at least not with the same boot parameters as the older kernel. The text was giving me various errors in "brcmfmac". Go figure! If anything, I would think a newer kernel is better on a relatively new computer.
All of the Mac products have the onboard Intel video (Intel HD Video, Intel Iris Pro etc), if it lists anything other than that, it was one of the higher end options that included dedicated graphics, in your case the Radeon M9 M390. My MacBook Pro has Intel Iris Pro + GeForce GT 750M. Any of the lower end offerings, including iMacs and Macbooks only had the onboard Intel video.
This is regularly an issue for operating systems (esp Linux) and isn't isolated to just Apple products. You see it a lot more in Laptops with dedicated Graphics that can swap video adapters on demand based on performance, or battery requirements.
Thanks, Scott. I have another clue about the problems I've had booting or installing distros on this Mac. According to an Arch Linux thread (here (https://bbs.archlinux.org/viewtopic.php?id=223178)), there's no non-apple driver for the 5120x2880 mode (5k). So Windows and Linux alike see the screen as 3840x2160. This includes Linux Mint, but Mint is the only distro I've found so far that will boot immediately without using the nomodeset as a parameter, AND AT THE SAME TIME, give me the option of switching resolution to the lower 4k standard (2560x1440). In that resolution, which is more than good enough for me, I have the option to magnify everything to 2x, which gives me nice text and windows to work from. I have since found a few other distros that will boot immediately with the nomodeset parameter (Ununtu itself, Debian xfce and Sparky Linux lxqt), but none allow me to lower the resolution to from 3840x2160 to 2560x1440. Without that option or a magnification setting between 1 and 2, the windows and text are either too tiny (magnification = 1) or too large (magnification =2). Therein lies my problem. Of equal importance, I cannot get even a Clonezilla usb disk to boot, which means I can't easily clone my Mint installation. (Yes I know I can do it with command line.) So while everything is working OK in Mint 18.2 with the default kernel, I'm feeling vulnerable on this machine without alternatives.
Seeing if there is a proper driver that you can download that is compatible with the kernel you're using should give you other resolution alternatives. Get a nice theme and icons and you can make Linux Mint look pretty good, though.
I have been looking for the right driver; my card is the Radeon R9 M395 (not 390 and not 395X). One site suggests that the right driver is the AMDGPU-PRO Driver, but this is built for Ubuntu 16.04 LTS and not 17.10. It isn't clear to me that there is an appropriate Radeon proprietary driver (or open source) for my card, for any Ubuntu newer than 16.04.
That would probably explain why Linux Mint 8.2 works then, having been based on 16.04. Did 16.04 support Flatpaks? I suppose if you really prefer Ubuntu you could install 16.04 and flatpak anywhere you need a newer version of an app. My guess is that it's actually tied to the kernel release series in Ubuntu 16.04 (4.4 series, I think).
I didn't try installing 16.04, but I did try running it from a live usb. It required either nomodeset or nointremap to boot up (I think the former), and when it did boot up, I had no control of resolution or screen magnification. Perhaps if I installed it and then installed the AMDGPU-PRO driver, I would get it back. I might try that when I have more time. But in the interim, the reason why Mint, based on 16.04, works and Ubuntu and other Ubuntu derivatives don't, remains a mystery to me.
Going back to that AMDGPU-PRO driver, it might work on 17.10 as well, but it was meant for the LTA release. I could try that by attempting an installation on the big hard drive inside the iMac, leaving the SSD with Mint on it alone.
I've done a few more tests with Ubuntu. Ubuntu 16.04 was easily started up with nomodeset, and easily installed. It booted up pretty quickly either in rescue mode, or faster if starting up with noapic nomodeset. The latter has to be there if you want it starting up quickly. Nointremap in place of nomodeset doesn't cut it (unlike Mint). The installed version doesn't show resolution options other than 3840x2160, but it does allow you to use settings to magnify window text and regular text. I found that I could use these to generate good settings, but I wanted to try more. The more was to install the amdgpu-pro driver. I could download and install it, and once I was able to boot it all the way. It resulted in smoother window movement, though no better than what I get on Mint. With this driver installed, settings now showed alternative lower resolutions, including the 2560x1440 that works well in Mint. So I tried that. Result: I could boot to the login window but no further. Putting in my password just brought back the same window. So I started over again, thinking I would see if this driver worked without messing with resolutions. Unfortunately, I forgot to follow one other instruction, which was to put me into the Video group. Now I can't go any further than the startup screen.
I'm going to try rescue mode, drop to a terminal and put me into the Video group, just to see if the driver works if I don't mess with resolution. I'm also going to try two other Ubuntu-based distros, Zorin and Ubuntu Budgie. It's still a mystery as to why Mint works without all this messing around and Ubuntu doesn't. One thing I did notice with Mint is that the command
lspci -k | grep -EA2 'VGA|3D'
shows that the amdgpu driver is being used. Not sure about Ubuntu.
Tried Zorin. It boots OK with nomodeset. Window movement appears to be more fluid than that of Ubuntu, but I'm not sure. In any case, no alternative resolutions show in settings, and there are none of the magnification settings that I can find in Ubuntu Unity. So not helpful.
Tried openSUSE, an education edition because vanilla openSUSE only gives an installer, not a live USB. I can't remember whether it required nomodeset or not, but it booted reasonably quickly to a KDE desktop. KDE seemed to have few options for scaling and the window movement wasn't fluid. Not worth looking further.
Went back to Ubuntu 17.10 and installed it. Works OK with nomodeset and scaling of fonts. Window movement OK but not so fluid. Installed Unity into 17.10. Windows move better and scaling is very good, but something went wrong and themes and icons went back to default. At any rate, 17.10 gnome is usable and I´ll play around with it another time. I´ll probably put 16.04 on it as well and see which works better (this time without the Radeon driver). They´re only there as backup because Mint works the best on this computer, despite the fact that the same driver is installed (amdgpu).
So I leave this set of tests with the following conclusions:
Conclusions:
- Installing a propietary Radeon driver appears to be a non-starter with my video card, at least until AMD puts out some updates
- No distro allows for the 5K resolution that this Mac is capable of
- Of all the distros I tried, only Mint (cinnamon) gives me the option to use a resolution other than 3840x2160
- The 2560x1440 resolution available on Mint, combined with scaling provides the best desktop experience I could get in Linux
- Desktop environment matters a lot on this iMac. The best DE for it seems to be Cinnamon, followed by Unity. (I haven't tried xfce or mate.)
- Mint (Cinnamon) provides the smoothest window movement options on this iMac. Next best is Ubuntu Unity.
OK, big breakthrough! I can now run the proprietary AMD driver (amdgpu-pro) on Ubuntu 16.04. The previous problem was that the non-amd intel video driver for the onboard video was interfering with the proprietary driver at startup. I found a posting that dealt with this, and it suggested a different install command:
./amdgpu-pro-install --px
... the --px replaced -y
That did it. Window movement is now much smoother than before, though not noticeably better than that of Mint. But I´m running Ubuntu on the HD, not the SSD like Mint, and I´m running it at higher resolution. Now I´ll have to decide whether it is worth replacing Mint with Ubuntu on the SSD. Whether I do or don´t, this is very significant. I now know that my Late 2015 iMac can run Ubuntu smoothly with high resolution. One other thing I want to try is to see if 17.10 will run with the amdgpu-pro driver.
One other neat thing about installing the amd driver in 16.04 - no need to put any special commands into the grub menu to get it to boot. So neither ¨nomodeset¨ or ¨nointremap¨ is needed. :)
Nice! Can you run it at native resolution now?
Quote from: Jason Wallwork on November 13, 2017, 05:00:39 PM
Nice! Can you run it at native resolution now?
Nope, 3840x2160 is still the max. The MacOS apparently does something unique to give 5K resolution on an iMac. You can run Windows on this Mac, and you'll get the same maximum resolution that Linux can give you. I don't know if that issue can or will ever be addressed. This was never a big deal to me. 2560x 1440 is plenty good on a 27" monitor. Even with 3840x2160 on Ubuntu and scaling, not all apps take that scaling. One that doesn't is Mendeley, a cross-platform reference manager that I use extensively. On Mint with the resolution set at 2560x1440, it is quite readable. On Ubuntu with the higher resolution, I have to wear my glasses to read it. So in the end, there may be minimal benefit to running Ubuntu with the proprietary driver vs running Mint without it.
I'm going to do more experiments to find out if I'm better off with Ubuntu, including using the proprietary driver at 2560x1440 resolution. But even if I end up sticking with Mint, the experiments are important to me. When I started with this iMac, Mint was the only distro that would boot in a reasonable period and run properly. That worried me, but now I know that this is no longer the case. Now if I can only figure out how to boot Clonezilla on this computer!
Cool. I think that even 4K is too high a resolution for that screen size. Seems overkill. At 40" sure, but 27" seems too small a screen for that resolution to use efficiently by most.
That's what I would have thought before I got my first 27" iMac, an old one that was given to me by a colleague who upgraded. 2560x1440 is beautiful on a 27" display, and the difference was noticeably better than the 1900x1080 I got on a 27" HP monitor. I do agree though, that the higher resolution on the Late 2015 iMac doesn't make any difference to me. Next time you're in Staples, take a look at one of these hi-res iMac monitors. I'm sure you'll see the difference, vs a 1080p 27" monitor in the same store.
I wasn't talking about 2560x1440; I was specifically talking about 4K on 27".
I agree that 2560 x 1440 would be fine on 27". The pixel density is probably about the same as 1920x1080 on 20-22" so text and icons, for example, should appear at about the same size - the desktop will just be roomier.
Well I just learned something. I always thought 4K was 2560x1440, but I see now that this is referred to as either QHD or WQHD. Looks like I either misread the 27" iMac ads or made the mistake by reading a recent 21.5" iMac ad. So I now agree with you; 4K has no obvious advantage over QHD on a 27" monitor. Thanks for pointing that out.
I ran a final set of tests. One of my big concerns was that Clonezilla wouldn't boot. I found a posting on the internet that suggested that sometimes the Debian version would work where the Ubuntu version wouldn't. The version that wouldn't boot was the Ubuntu-based alternative stable. The Debian stable version (2.5.2.31) did in fact boot! I also tried the most recent Ubuntu-based testing version (20171101-artful); my iMac didn't even see it.
Finally, I tried installing the amdgpu-pro drivers on Ubuntu 17.10. Didn't work; there was even an error during installation. I tried booting with it anyway and it wouldn't boot regardless of grub parameter. I was able to boot into rescue mode and uninstall the drivers. So I still have 17.10 to play with, should AMD issue an update. (They probably won't until the next Ubuntu LTS.)
What I haven't tried is installing the driver on Mint 18.2. Window movement is already OK on it, and the only thing not working to Ubuntu standard on it are the Microsoft Office 2010 programs on Wine (via Crossover). For some reason, their boot time varies wildly from almost immediate to ~15 sec, and I don't know why. (I never had this problem on Ubuntu.) While annoying when in long boot, it isn't a show stopper. Now I'll just have to decide whether to use Mint 18.2 or Ubuntu 16.04 as my default.
Quote from: fox on November 14, 2017, 06:43:18 AM
Well I just learned something. I always thought 4K was 2560x1440, but I see now that this is referred to as either QHD or WQHD. Looks like I either misread the 27" iMac ads or made the mistake by reading a recent 21.5" iMac ad. So I now agree with you; 4K has no obvious advantage over QHD on a 27" monitor. Thanks for pointing that out.
No problem. 4K refers to the number of horizontal pixels being around 4,000.
Quote from: fox on November 14, 2017, 11:23:07 AM
What I haven't tried is installing the driver on Mint 18.2. Window movement is already OK on it, and the only thing not working to Ubuntu standard on it are the Microsoft Office 2010 programs on Wine (via Crossover). For some reason, their boot time varies wildly from almost immediate to ~15 sec, and I don't know why. (I never had this problem on Ubuntu.)
I think I have finally figured that out. I had two wine-type installations of MS Office 2010 running on Mint; one in Crossover and the other in PlayonLinux. I eliminated the later after it got confusing as to which one would start. But the system didn't eliminate it as the default app for starting up an Office file. Clicking on that default must have caused a delay as the system looked for that program in the POL virtual drive. When I changed the default opening program to the Crossover version, Office files now open up instantly.
At this point there are no remaining problems with my Mint 18.2 installation, and windowing is actually smoother than on Ubuntu 16.04, even with the latter using the amdgpu-pro driver. I'm going to keep both on my drive, but it looks like I am now a Linux Mint convert (at least on this computer). If I have no reason to switch after a few months, I'm going to have to think about donating to Mint for giving me such a great experience on this non-Linux-friendly iMac. :)
Cool. I think it's good when we give a little back to the community like that, too. I donated quite a while ago to the Ubuntu MATE guys back when I was using it regularly. Probably do so soon for the LM guys, too.
I can add a new interesting finding to the saga. I downloaded openSUSE Tumbleweed Live (KDE version) the other day, put it on a USB stick and tried to boot it on my late 2015 5K iMac. And guess what? It booted up right away without any special mode setting options! I had tried openSUSE Leap before and it didn't, but it was some community version because Leap doesn't have a live version. The difference, I think, is that Tumbleweed has the latest kernel (4.15.5-1), and I read earlier that kernel 4.15 included some improvements on the open source AMDGPU driver. Also, the window was fluid. A bunch of dpi settings were available, but unfortunately the 2560x1440 gave something distorted, and several other settings ended up blanking my display. I tried with the Gnome version and got the same results. But in Gnome you can universally scale fonts and in KDE, the same. This gives me hope that the next round of distros, including Ubuntu 18.04, will run well on this iMac, even without a proprietary AMD driver.
Incidentally, openSUSE Tumbleweed live sees my Broadcom wifi; something that Ubuntu and most Debian derivatives don't.
Further good news on the 5k iMac/AMDGPU front. Ubuntu 18.04 (Bionic Beaver) will use version 4.15 of the Linux kernel, and this kernel does have vastly improved support for the newer AMD GPU's. I just downloaded the daily build and tried the live USB version on my Late 2015 iMac. It boots right up with the default Grub mode settings. Once booted up, the default open source AMDGPU is very functional. You get alternative monitor settings (I can verify that 2560x1440 works), and window movement is smooth! This is actually better performance than I got with the live USB for openSUSE Tumbleweed in that the display setting change actually works. I don't know why there is this difference between Ubuntu and openSUSE, but perhaps the latter is missing a library or some other package needed for proper functioning that is present in the Ubuntu live USB. There was a slight difference in kernel: 4.15.0-10-generic for Ubuntu and 4.15.5.-1 for openSUSE Tumbleweed. I doubt that this difference would be the cause, but I can't rule it out.
All of this is cause for rejoicing! It means that I no longer have to worry that my recent iMac won't function right with newer Linux distros and most important for me, that 18.04 works out of the box. I am no longer a forced convert to Linux Mint. That doesn't necessarily mean I'll stop using it, but now I have choice :)
Nicely done. Maybe they're not loading the same driver? Try this command in the terminal for both and compare the output (assuming that it's in other distros other than LM):
inxi -xG
Drivers are different.
In openSUSE, I get "modesetting,ati(unloaded fbdev,vesa,radeon)"
In Ubuntu, I get "amdgpu" as well as openGL version 4.5 Mesa 17.3.3, direct rendering: yes
Can you interpret the openSUSE output? What I'm thinking it did was not install amdgpu, but rather an ati driver and it blacklisted fbdev, vesa and radeon drivers that might conflict with it. I seem to recall fbdev being one of the thinks that some usb distro boots were stuck on, and also some advice on the internet to blacklist radeon. If so, then I now have another important piece of information, which is to blacklist those drivers in the grub bootup sequence, after which perhaps any distro will boot on this iMac? What do you think?
Perhaps as well, if I wanted to install openSUSE, I might be able to download and install the open source amdgpu driver, which would add back full modesetting functionality. Or perhaps openSUSE would install this driver automatically if I installed the distro instead of running it from a live USB.
Quote from: fox on February 26, 2018, 03:41:04 PM
Drivers are different.
In openSUSE, I get "modesetting,ati(unloaded fbdev,vesa,radeon)"
In Ubuntu, I get "amdgpu" as well as openGL version 4.5 Mesa 17.3.3, direct rendering: yes
Can you interpret the openSUSE output? What I'm thinking it did was not install amdgpu, but rather an ati driver and it blacklisted fbdev, vesa and radeon drivers that might conflict with it. I seem to recall fbdev being one of the thinks that some usb distro boots were stuck on, and also some advice on the internet to blacklist radeon. If so, then I now have another important piece of information, which is to blacklist those drivers in the grub bootup sequence, after which perhaps any distro will boot on this iMac? What do you think?
I only recently found about using the inxi command from Linux Mint forums, incidentally. But what you're saying sounds correct. But you mentioned that it doesn't work as well in OpenSUSE so I'm thinking you don't want to use it's procedure with other distros. Fbdev is related to framebuffer which is essentially a mode that will work with every graphics card/chipset but its performance isn't very good. When Linux distros first start up, before they get to the graphical login(if they have one), it's using framebuffer mode, I believe. Though I might be confusing that with VESA.
QuotePerhaps as well, if I wanted to install openSUSE, I might be able to download and install the open source amdgpu driver, which would add back full modesetting functionality. Or perhaps openSUSE would install this driver automatically if I installed the distro instead of running it from a live USB.
I think that this would be a better approach. If you check the support pages for opensuse, they probably have information on installing it. Their docs can be quite extensive.
Jason, that inxi -xG command is very useful. I just ran it on my Mint 18.3 installation, which as you might recall, was until recently the only distro that booted up right away on this iMac using the less drastic "nointremap" grub parameter. Here is the output:
Graphics: Card: Advanced Micro Devices [AMD/ATI] Device 6920 bus-ID: 01:00.0
Display Server: X.Org 1.18.4 drivers: ati,amdgpu (unloaded: fbdev,vesa,radeon)
Resolution: 2560x1440@59.95hz
GLX Renderer: AMD RADEON R9 M390X (AMD TONGA / DRM 3.3.0 / 4.8.0-53-generic, LLVM 5.0.0)
GLX Version: 3.0 Mesa 17.2.8 Direct Rendering: Yes
As you can see, it's a hybrid between the output from Ubuntu 18.04 daily build and openSUSE Tumbleweed. It is using the AMDGPU driver, but it blacklisted (I think that's how you interpret "unloaded") fbdev, vesa and radeon. So thanks to you, I think I finally understand what the problem has been in getting various distros to boot up on this iMac: conflict with other drivers and the absence of the open source AMDGPU driver, which seems to require some other software to work (firmware-linux, clang and llvm). At least the first one isn't necessarily present on a live USB or a default installation of some distros, as it is a closed source firmware blob. For those, the answer seems to be to install them, add the software, and make sure the offending drivers are blacklisted.
I don't think "unloaded" means blacklisted. I believe it just means that Linux loaded those modules (drivers, in this case) early on and when it was able to load more modules after mounting the root file system, it saw a better driver, unloaded those and loaded the better one and yes, it had to unload the others because they would likely conflict. But I believe the same thing happens at every boot (loading those modules and then unloading them once the AMDGPU driver was found probably on the root filesystem).
OK, got it. Unfortunately, this brings me back to square one with regarding to getting live USB's to boot correctly. If the distro (like openSUSE) isn't pre-programmed to load the AMDGPU driver, how do I get it working? In the case of openSUSE Tumbleweed, I was partly successful because it loaded "modesetting" and "ati". But I don't know how it did that.
Look up how to load and unload modules in Linux. If you know the module you need and it's available it shoudln't be hard to load on the fly. As far as trying to get it with Live versions, I woudln't bother, as long as you get at least some workable display. Live versions are meant to try out Linux distros. They're not really meant to run from permanently from unless you like running on a much slower USB drive. This might help but I admit I haven't tried it. Back in the day you used to have to modprobe to get lots of hardware to work:
https://askubuntu.com/questions/961129/how-can-i-force-the-amdgpu-module-to-load-after-other-modules (https://askubuntu.com/questions/961129/how-can-i-force-the-amdgpu-module-to-load-after-other-modules)
Though that question is specifically for Ubuntu (or LM) you can probably find a customized version for other distros.
Interestingly enough, when I checked my Ubuntu 16.04 distro with your inxi -xG command, I got the following:
Graphics: Card: Advanced Micro Devices [AMD/ATI] Device 6920 bus-ID: 01:00.0
Display Server: X.Org 1.19.5 drivers: ati,amdgpu (unloaded: fbdev,vesa,radeon)
Resolution: 2560x1440@59.95hz
GLX Renderer: AMD RADEON R9 M390X
GLX Version: 4.5.13505 - CPC 17.50.2.13 Direct Rendering: Yes
This is after I downloaded and installed the AMDGPU-pro driver, but the important part is the same drivers are unloaded. I didn't set up anything to do that other than installed the closed source driver, so it appears that an "AMD-aware" distro does this automatically, at least with a kernel below 4.14. Mint is an oddity. It works fine on kernel 4.8 on my 5k iMac and always has, but upgrade the kernel to 4.13 and it chokes at bootup.
Quote from: Jason Wallwork on February 26, 2018, 04:27:52 PM
Quote from: fox on February 26, 2018, 03:41:04 PM
Drivers are different.
In openSUSE, I get "modesetting,ati(unloaded fbdev,vesa,radeon)"
In Ubuntu, I get "amdgpu" as well as openGL version 4.5 Mesa 17.3.3, direct rendering: yes
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QuotePerhaps as well, if I wanted to install openSUSE, I might be able to download and install the open source amdgpu driver, which would add back full modesetting functionality. Or perhaps openSUSE would install this driver automatically if I installed the distro instead of running it from a live USB.
I think that this would be a better approach. If you check the support pages for opensuse, they probably have information on installing it. Their docs can be quite extensive.
I took your advice and found that to get the amdgpu driver, you need the file "xf86-video-amdgpu. There is a candidate for this in the openSUSE Tumbleweed, so I downloaded it and installed it. It worked! When I rebooted and checked the video setting with inxi -xG, I got:
Graphics: Card: Advanced Micro Devices [AMD/ATI] Device 6920
bus-ID: 01:00.0
Display Server: x11 (X.org 1.19.6 )
drivers: ati,amdgpu (unloaded: modesetting,fbdev,vesa,radeon)Note that the "modesetting" driver was unloaded this time, replaced by amdgpu. Now the modes work, and they work properly! Note that all this is from a live USB; I haven't installed it. What's neat about the openSUSE Tumbleweed live distro is that it saves changes. Colour me very impressed with openSUSE Tumbleweed. I'm actually tempted to install it, and I would be willing to demo it at a future meeting (KDE version even).
Interesting! And good job on working it out. I think you might have done enough investigation to do a future presentation on troubleshooting graphics, too.