{"id":452,"date":"2026-10-28T11:17:01","date_gmt":"2026-10-28T18:17:01","guid":{"rendered":"https:\/\/www.lucaswilliams.net\/?p=452"},"modified":"2026-10-28T11:17:03","modified_gmt":"2026-10-28T18:17:03","slug":"updating-imac-2015-5k-model-to-use-amdgpu-kernel-drivers-in-ubuntu-26-04","status":"publish","type":"post","link":"https:\/\/www.lucaswilliams.net\/index.php\/2026\/10\/28\/updating-imac-2015-5k-model-to-use-amdgpu-kernel-drivers-in-ubuntu-26-04\/","title":{"rendered":"Updating iMac 2015 5K model to use AMDGPU kernel drivers in Ubuntu 26.04"},"content":{"rendered":"\n

Hello. I acquired a 2015 iMac with 5K display. Unfortunatly this Mac doesn’t support the latest version of MacOS, so I decided that I would install Ubuntu on it. The installation was straight forward. I have a blog on this site that details how to install Linux on Apple systems. Just following that Blog<\/a> to install Ubuntu on an iMac.<\/p>\n\n\n\n

So I have been running it pretty consistantly and haven’t had any issues until I noticed that if I try to stream video through Brave or Chrome broswers, or really any web browser, the performance was terrible. I did find that I could disable hardware accelleration in Brave and Chrome, but some sites it worked, most it did not.<\/p>\n\n\n\n

After some online searching I found out that Ubuntu 26.04 by default on older AMD Graphics cards, which this system does have, it uses the older radeon kernel driver. So, as a test, I decided to try to force the newer amdgpu driver and use that instead.<\/p>\n\n\n\n

To do this I had to black list the radeon driver and enable the amdgpu driver, and then I found a couple of other parameters to get this working smoothly.<\/p>\n\n\n\n

First, you need to update the \/etc\/default\/grub<\/code> configuration. I like to use vi so:<\/p>\n\n\n\n

sudo vi \/etc\/default\/grub<\/code><\/pre>\n\n\n\n
Once I have the file open, look for the line:<\/p>\n\n\n\n
GRUB_CMDLINE_LINUX_DEFAULT=\"quiet splash\"<\/code><\/pre>\n\n\n\n
We’re going to modify this line to blacklist the radeon driver and use the amdgpu driver. After splash<\/code>, we need to enter the following:<\/p>\n\n\n\n
radeon.cik_support=0 amdgpu.cik_support=1 amdgpu.dc=1 amdgpu.ppfeaturemask=0xfff7bffd<\/code><\/pre>\n\n\n\n
The full GRUB_CMDLINE_LINUX_DEFAULT<\/code> should look like this:<\/p>\n\n\n\n
GRUB_CMDLINE_LINUX_DEFAULT=\"quiet splash radeon.cik_support=0 amdgpu.cik_support=1 amdgpu.dc=1 amdgpu.ppfeaturemask=0xfff7bffd\"<\/code><\/pre>\n\n\n\n
Save the configuration by pressing the ESC key and typing :wq<\/code> to save and quit vi. <\/p>\n\n\n\n
Next, reboot your computer. Once it starts up, you can run the following command to verify that you are using the amdgpu driver:<\/p>\n\n\n\n
lspci -k | grep -E -A 3 \"VGA|3D\"<\/code><\/pre>\n\n\n\n
This will be the output:<\/p>\n\n\n\n
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD\/ATI] Amethyst [Radeon R9 M395\/ M395X Mac Edition] (rev 01)\n        Subsystem: Apple Inc. Device 014c\n        Kernel driver in use: amdgpu\n        Kernel modules: amdgpu<\/code><\/pre>\n\n\n\n
Now, if you disabled graphic accelleration in your web browser, you can re-enable it and try going to a site like YouTube and stream a video and you will notice it is working correctly and streaming normally.<\/p>\n\n\n\n
I hope this helps.<\/p>\n","protected":false},"excerpt":{"rendered":"
Hello. I acquired a 2015 iMac with 5K display. Unfortunatly this Mac doesn’t support the latest version of MacOS, so I decided that I would install Ubuntu on it. The installation was straight forward. I have a blog on this site that details how to install Linux on Apple systems. Just following that Blog to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[94,168,37,185,174,175,6],"tags":[176,181,182,184,27,21,55,180,92,183,22,5],"class_list":["post-452","post","type-post","status-publish","format-standard","hentry","category-apple","category-desktop","category-howto","category-imac","category-kernel","category-modules","category-ubuntu","tag-26-04","tag-amd","tag-amdgpu","tag-apple","tag-canonical","tag-configure","tag-howto","tag-imac","tag-mac","tag-radeon","tag-setup","tag-ubuntu"],"_links":{"self":[{"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/posts\/452","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/comments?post=452"}],"version-history":[{"count":1,"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/posts\/452\/revisions"}],"predecessor-version":[{"id":453,"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/posts\/452\/revisions\/453"}],"wp:attachment":[{"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/media?parent=452"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/categories?post=452"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lucaswilliams.net\/index.php\/wp-json\/wp\/v2\/tags?post=452"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}