Differences

This shows you the differences between two versions of the page.

--- linux:notes:kernel_parameters [2024/09/04 22:04] – [IOMMU] Sean Rhone
+++ linux:notes:kernel_parameters [2025/04/22 01:08] (current) – Sean Rhone
@@ Line 3: / Line 3: @@
   * Various kernel options
   * https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
-  * :!: systemd-boot does not like apostrophes '''like this' '', but GRUB handles it fine
-====== General ======
+===== systemd-boot =====
-===== Low-Latency =====
+  * :!: 2024: ''systemd-boot'' doesn't handle typewriter apostrophes '''like this' '', but GRUB handles it fine ((above kernel params page mentions double-quote usage))
+  * :!: 2024/05/18: ''systemd-boot'' on [[linux;distros;opensuse_tumbleweed_gnome|oS TW]] doesn't delete old ''initrd''s automatically, doesn't handle typewriter apostrophes, doesn't support ''dracut.conf'' settings, and doesn't seem faster than GRUB
-****
+====== Resources ======
-  preempt='full' threadirqs nohz='off'
+===== General =====
+  * https://fwupd.github.io/libfwupdplugin/hsi.html#org.fwupd.hsi.SuspendToIdle
+  * :!: ''iommu=off'' should not be used ([[http://www.xillybus.com/tutorials/iommu-swiotlb-linux|source]])
+  * https://docs.kernel.org/fb/modedb.html
+  * https://fwupd.github.io/libfwupdplugin/hsi.html#org.fwupd.hsi.EncryptedRam
 ===== CPU Idle =====
@@ Line 18: / Line 23: @@
   * https://docs.kernel.org/admin-guide/pm/cpuidle.html
   * https://community.intel.com/t5/Software-Tuning-Performance/Benchmark-performance-increases-with-deeper-C-states-linux/td-p/1051623
-  idle=halt
 ===== OSI =====
@@ Line 25: / Line 28: @@
   * https://forum.manjaro.org/t/how-to-choose-the-proper-acpi-kernel-argument/1405
   * https://learn.microsoft.com/en-us/windows-hardware/drivers/acpi/winacpi-osi
-  acpi_osi='Linux'
-  acpi_osi='Windows 2017'
 ==== Spinesnap ====
@@ Line 37: / Line 36: @@
   acpi_osi='!' acpi_osi='Windows 2017'
-===== Reboot =====
+====== Spinesnap ======
-  * Does hard reboots
+===== General =====
-  * :!: ''reboot=efi'' causes a Dell Latitude 5591 to not reboot
-  reboot='pci'
+****
-  reboot='efi'
+<code>acpi_osi='Linux' reboot='pci' nohz='off' preempt='none' cpuidle.off='1'</code>
-===== Modern Standby =====
+===== PCI =====
-  * https://fwupd.github.io/libfwupdplugin/hsi.html#org.fwupd.hsi.SuspendToIdle
+****
-  mem_sleep_default='s2idle'
+<code>enable_mtrr_cleanup iomem='relaxed' pcie_ports='native' pci='nocrs,pcie_bus_perf,realloc,pcie_scan_all,big_root_window'</code>
-===== IOMMU =====
+===== i915 =====
-  * :!: ''iommu=off'' should not be used ([[http://www.xillybus.com/tutorials/iommu-swiotlb-linux|source]])
+****
-  iommu='pt'
+<code>i915.enable_fbc='0' i915.enable_psr='0' i915.panel_use_ssc='0' i915.enable_guc='3' i915.guc_log_level='0' i915.nuclear_pageflip='1' i915.enable_hangcheck='0'</code>
-===== PCI =====
+===== Mitigations =====
 ****
-  pci='pcie_bus_perf,realloc,pcie_scan_all,big_root_window'
+<code>mitigations='off' i915.mitigations='off'</code>
-===== Interrupt Remapping =====
+===== NVMe =====
 ****
-  intremap='off'
+<code>nvme.noacpi='1' nvme.poll_queues='4' nvme.use_threaded_interrupts='1'</code>
-===== Custom Resolution =====
+===== Power-saving =====
-  * https://docs.kernel.org/fb/modedb.html
+****
-  * Necessary for Wayland, and also works on Xorg as an alternative to ''xorg.conf''
+<code>nowatchdog modprobe.blacklist='iTCO_wdt' tsc='nowatchdog' ahci.mobile_lpm_policy='1' iwlmvm.power_scheme='1' nvme_core.default_ps_max_latency_us='0' pcie_aspm='off' pcie_port_pm='off' snd_hda_intel.power_save='0' usbcore.autosuspend='-1'</code>
-  * :?: ''HDMI-A-1'' is the same for a AMD 6600 XT and Intel UHD 630; it's possible this works for all GPUs or there's some standard?
-==== Acer S721HL ====
+===== Display =====
-  * Increase refresh rate for 1080p from default 60Hz to 75Hz
+****
-  video='HDMI-A-1:1920x1080MR@75'
+<code>video='HDMI-A-1:1920x1080MR@75'</code>
-==== TCL 55S405 ====
+===== IOMMU =====
-  * Solves instability on some AMD GPUs at 4K@60Hz on HDMI
+****
-  * 2024/04/29: From old notes and untested with ''M''
-  video='HDMI-A-1:3840x2160MR@60'
+<code>swiotlb='noforce' iommu='force' intel_iommu='on'</code>
-====== AMD ======
+====== Other ======
-===== Memory Encryption =====
+<code>rootflags='data=writeback'</code>
-  * https://fwupd.github.io/libfwupdplugin/hsi.html#org.fwupd.hsi.EncryptedRam
+<code>threadirqs</code>
-  * :!: Requires CPU SVM to be enabled in BIOS ((AMDGPU will likely panic on-boot if ''mem_encrypt'' is enabled without SVM))
-  * Disable TSME in BIOS if using this
+<code>idle=halt</code>
+<code>mem_sleep_default='s2idle'</code>
+<code>intremap='off'</code>
+<code>mem_encrypt='on'</code>
+===== TPM Integrity =====
+  * https://www.phoronix.com/news/Linux-TPM-Disable-PCR-Integrity
+  * TODO: Option name (probably ''off'')
-  mem_encrypt='on'
+<code>tpm.disable_pcr_integrity=</code>
 ====== AMDGPU ======
@@ Line 118: / Line 125: @@
   cat '/sys/module/amdgpu/parameters/ppfeaturemask'
-====== Intel ======
+===== Disable PSR =====
-===== i915 =====
+  * :?: ''0x15'' was seen somewhere for something
+  * 2025/03/04: Untested
-****
-  i915.enable_dc=0 i915.enable_fbc=0 i915.enable_psr=0 i915.enable_psr2_sel_fetch=0 i915.enable_hangcheck=0 i915.panel_use_ssc=0 i915.guc_log_level=0 i915.nuclear_pageflip=1 i915.request_timeout_ms=200000 i915.enable_guc=3
-===== IOMMU =====
-  * Requires CPU SVM to be enabled in BIOS
-  intel_iommu='on'
-===== Firmware =====
-  * This enables GuC and HuC firmware loading ((do this even if unsure because seemingly not even Intel is aware of how certain hardware pre-12th-gen/AL loads the firmware; worst-case it just won't load))
-  i915.enable_guc='3'
+  amdgpu.dcdebugmask=0x10
 ====== NVIDIA ======
@@ Line 185: / Line 179: @@
   * https://github.com/ckb-next/ckb-next/wiki/Troubleshooting#usbhid-quirks
   * :!: Seemingly only needed with the mouse plugged directly to the motherboard, and not through USB-C docks
+  * :?: 2024/09/30: Without that quirk, mouse failed immediately after setting ''preempt=none'' from a USB-C dock
   usbcore.quirks='1b1c:1b75:bgmn'
-====== Coreboot ======
-===== Flashing =====
-  * This is needed to relax permissions for Coreboot firmware to be flashed internally
-  * :!: This should be removed after flashing
-  iomem='relaxed'