GRUB_CMDLINE_LINUX_DEFAULT=“quiet splash amdgpu.ppfeaturemask=0xffffffff”
🧩 1. What is GRUB_CMDLINE_LINUX_DEFAULT?
-
It’s a GRUB config variable found in
/etc/default/grub. -
It defines default kernel command-line parameters passed on normal boots (not recovery mode).
-
These parameters affect the Linux kernel’s behavior during and after boot.
🧩 2. quiet splash – What are these?
| Parameter | Meaning |
|---|---|
quiet | Suppresses most boot messages from the kernel. You won’t see things like “Started XYZ”, “Mounted ABC”, etc. |
splash | Tells the init system (and display manager) to show a splash screen (like a logo or animation). |
Used together, quiet splash gives a clean boot screen (e.g., Ubuntu logo instead of kernel logs).
🧠 You can remove these if you want to see verbose boot messages, e.g. for troubleshooting.
🧩 3. amdgpu.ppfeaturemask=0xffffffff – What is this?
-
This is a kernel parameter for AMD GPU driver (
amdgpu). -
ppfeaturemaskcontrols PowerPlay features — like overclocking, fan curve control, power states, etc. -
By default, many of these are locked down by the driver.
By setting:
amdgpu.ppfeaturemask=0xffffffff
You enable all PowerPlay features, even undocumented or unsupported ones.
🛠️ Why use this?
-
To control GPU fan curve, power limits, or clock speeds from userspace using tools like:
-
rocm-smi -
pp_od_clk_voltage -
Custom fan/OC scripts
-
⚠️ Be careful: Enabling unsupported features can cause instability or damage if you’re careless.
🧪 How to Apply Changes
-
Edit the file:
sudo nano /etc/default/grub -
Modify the
GRUB_CMDLINE_LINUX_DEFAULTline. -
Save and run:
sudo update-grub -
Reboot.
🧠 How to Learn About Them
🔹 1. Official Linux Kernel Docs
-
Canonical source for many options.
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🔗 https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
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Contains nearly all upstream-supported options.
-
Searchable by keyword (e.g.,
amdgpu,quiet,nomodeset, etc.)
🔹 2. modinfo for Module-Specific Parameters
For driver/module-specific options (like amdgpu.ppfeaturemask):
bash
CopyEdit
modinfo amdgpu
Gives info about parameters, description, and default values (if documented).
🔹 3. Read Current Boot Parameters
bash
CopyEdit
cat /proc/cmdline
Shows what parameters were passed at boot time.