iMac getting black screen from live usb

I really like Garuda and have used it on my laptop.

On my iMac 27" 2011 with faulty AMD card, I have MX Linux 21 installed and running.

When i run from garuda kde live usb, I get a black screen after grub menu is visible. I have used different usb makers like balenaetcher, fedora writer and mxlive usb maker and had the same result.

I have tried radeon,modeset=0 but this has not worked

Any help is greatly appreciated.

Below is system information.

System:    Host: <filter> Kernel: 5.10.0-8-amd64 x86_64 bits: 64 compiler: N/A 
           parameters: BOOT_IMAGE=/boot/vmlinuz-5.10.0-8-amd64 
           root=UUID=<filter> ro quiet nomodeset splash 
           Desktop: Gnome 40.2 wm: gnome-shell dm: LightDM 1.26.0 
           Distro: MX-21_beta1_x64 Wildflower July 27  2021 base: Debian GNU/Linux 11 (bullseye) 
Machine:   Type: Desktop System: Apple product: iMac12,2 v: 1.0 serial: <filter> Chassis: 
           type: 13 v: Mac-942B59F58194171B serial: <filter> 
           Mobo: Apple model: Mac-942B59F58194171B v: iMac12,2 serial: <filter> UEFI: Apple 
           v: date: 06/14/2019 
CPU:       Topology: Quad Core model: Intel Core i5-2400 bits: 64 type: MCP arch: Sandy Bridge 
           family: 6 model-id: 2A (42) stepping: 7 microcode: 2F L2 cache: 6144 KiB 
           flags: avx lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 24800 
           Speed: 1808 MHz min/max: 1600/3400 MHz Core speeds (MHz): 1: 1871 2: 1922 3: 1878 
           4: 1855 
           Vulnerabilities: Type: itlb_multihit status: KVM: VMX disabled 
           Type: l1tf mitigation: PTE Inversion; VMX: conditional cache flushes, SMT disabled 
           Type: mds mitigation: Clear CPU buffers; SMT disabled 
           Type: meltdown mitigation: PTI 
           Type: spec_store_bypass 
           mitigation: Speculative Store Bypass disabled via prctl and seccomp 
           Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer sanitization 
           Type: spectre_v2 mitigation: Full generic retpoline, IBPB: conditional, IBRS_FW, 
           STIBP: disabled, RSB filling 
           Type: srbds status: Not affected 
           Type: tsx_async_abort status: Not affected 
Graphics:  Device-1: Intel 2nd Generation Core Processor Family Integrated Graphics 
           vendor: Apple driver: N/A bus ID: 00:02.0 chip ID: 8086:0102 
           Device-2: AMD Blackcomb [Radeon HD 6970M/6990M] vendor: Apple driver: N/A 
           bus ID: 01:00.0 chip ID: 1002:6720 
           Display: x11 server: X.Org 1.20.11 driver: none unloaded: fbdev 
           compositor: gnome-shell resolution: 2560x1440~93Hz 
           OpenGL: renderer: llvmpipe (LLVM 11.0.1 256 bits) v: 4.5 Mesa 20.3.5 compat-v: 3.1 
           direct render: Yes 
Audio:     Device-1: Intel 6 Series/C200 Series Family High Definition Audio 
           driver: snd_hda_intel v: kernel bus ID: 00:1b.0 chip ID: 8086:1c20 
           Device-2: AMD Barts HDMI Audio [Radeon HD 6790/6850/6870 / 7720 OEM] vendor: Apple 
           driver: snd_hda_intel v: kernel bus ID: 01:00.1 chip ID: 1002:aa88 
           Sound Server: ALSA v: k5.10.0-8-amd64 
Network:   Device-1: Broadcom and subsidiaries NetXtreme BCM57765 Gigabit Ethernet PCIe 
           driver: tg3 v: kernel port: 2000 bus ID: 02:00.0 chip ID: 14e4:16b4 
           IF: eth0 state: down mac: <filter> 
           Device-2: Qualcomm Atheros AR93xx Wireless Network Adapter 
           vendor: Apple AirPort Extreme driver: ath9k v: kernel port: 2000 bus ID: 03:00.0 
           chip ID: 168c:0030 
           IF: wlan0 state: up mac: <filter> 
Drives:    Local Storage: total: 960.33 GiB used: 17.77 GiB (1.9%) 
           ID-1: /dev/sda vendor: Western Digital model: WD1001FALS-403AA0 size: 931.51 GiB 
           block size: physical: 512 B logical: 512 B speed: 3.0 Gb/s rotation: 7200 rpm 
           serial: <filter> rev: 1D02 scheme: GPT 
           ID-2: /dev/sdc type: USB vendor: Kingston model: DataTraveler 3.0 size: 28.82 GiB 
           block size: physical: 512 B logical: 512 B serial: <filter> scheme: MBR 
Partition: ID-1: / raw size: 923.23 GiB size: 907.67 GiB (98.31%) used: 17.77 GiB (2.0%) 
           fs: ext4 dev: /dev/sda2 
           ID-2: swap-1 size: 8.00 GiB used: 0 KiB (0.0%) fs: swap swappiness: 15 (default 60) 
           cache pressure: 100 (default) dev: /dev/sda3 
Sensors:   System Temperatures: cpu: 52.0 C mobo: N/A 
           Fan Speeds (RPM): cpu: 1124 
Info:      Processes: 232 Uptime: 34m Memory: 19.53 GiB used: 1.67 GiB (8.5%) Init: SysVinit 
           v: 2.96 runlevel: 5 default: 5 Compilers: gcc: 10.2.1 alt: 10 Shell: quick-system-in 
           running in: quick-system-in inxi: 3.0.36 

I mean... this is a decade-old system with a known hardware issue.

What are you expecting here? Magic?

Can you disable the faulty card in the BIOS/UEFI/whatever Macs have?


It's not possible to disable the AMD Blackcomb [Radeon HD 6970M/6990M] card directly in an iMac.

MX Linux through grub kernel commands have disabled the amd radeon gpu, but looking for similar arch commands that will do the trick in garuda? Is it because MX Linux is debian based that the same kernel commands don't work?


Imacs dont have a BIOS? sorry i haven't used any apple computers in my life, so dont know about this


the issue is not about Bios settings as I can run the usb, the issue is how to disable the discreae amd gpu from grub by pressing 'e' and what kernel commands i need to enter to make it use the internal intel gpu?

There may be other options, e.g. iMac 27' Mid 2011 GPU Issue | MacRumors Forums

What commands have you tried, and what effect do they have?

No what I meant, is in the bios there is an option to disable the discrete gpu.

Try to find your MXLinux advised commands, for convenience.

You may try some of these:

radeon.si_support=0 amdgpu.si_support=0
radeon.cik_support=0 amdgpu.cik_support=0

I'm running Garuda on my mid 2011 21.5" iMac without any issues. I'm not sure you're going to get past the faulty AMD GPU issue. Good news is the GPUs for these are SUPER cheap and pretty easy to replace if you're not nervous to take apart your iMac.

If I were you I'd look for a mxm-b GPU like a GTX 770m 3GB from a Dell Alienware they can be had sub $100 if you look. And you'll get a massive boost in performance over the factory ATi Radeon HD 6770m 512MB GPU. There are other much cheaper nVidia cards too you can put in. You should have a 3 pipe GPU heatsink, and if you're not after any GPU performance for any gaming, I'd throw in a mxm-a GPU as they are SUPER cheap, and your factory heatsink will super cool one of those.

Here is a great resource for how to replace, and what GPUs are known to work.

If interested I have a couple mxm-a GPUS that will work you can message me if you like.

Good luck.

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