View source for Kernel parameters and module options

Reference for every kernel command-line and <code>nvidia</code> module option that appears in the unlock work. The
modprobe lines usually live in <code>/etc/modprobe.d/cmp-pcie-gen2.conf</code> (or <code>-gen3</code>), written by the
installer; kernel-cmdline options go in GRUB or <code>/etc/kernel/cmdline</code>.

== Kernel command line ==

{| class="wikitable"
! Option !! What it does !! Source
|-
| <code>iomem=relaxed</code> || Required for [[RIR fuse burn|170hx-rir-tool]] to read BAR0 fuse registers at all; also needed on EndeavourOS-type distros. || {{Source|lycorascence|2026-10-20|https://discord.com/channels/1518634379604136178/1518695328008638516/1562147741092806787}}
|-
| <code>intel_iommu=on</code> / <code>amd_iommu=on</code> plus <code>iommu=pt</code> || IOMMU in passthrough mode; appended by the cmpunlocker installer by default (backs up the boot file). Must also enable VT-d / AMD-Vi in BIOS. || cmpunlocker install.sh
|-
| <code>systemd.mask=gen2.service</code> || Recovery boot option: skip the early-boot [[Gen2 link retrain]] hammer if it misbehaves. || cmpunlocker install output
|-
| <code>NVreg_EnableGpuFirmware=0</code> (as <code>nvidia.NVreg_EnableGpuFirmware=0</code>) || Disable GSP; with a dual-stack driver the unlock survives a proprietary-driver reload with no GSP panics. Needs the closed/CPU-RM driver. See [[VBIOS and firmware]]. || {{Source|zarknoth|2026-10-27|https://discord.com/channels/1518634379604136178/1518695328008638516/1564547690019160145}}
|}

LTS kernel plus the oldest cmpunlocker-supported driver avoids <code>CONFIG_IO_DEVMEM_STRICT</code> blocking the RIR
tool. {{Source|lycorascence|2026-10-23|https://discord.com/channels/1518634379604136178/1518695328008638516/1563135463106289716}}

== nvidia module options (NVreg_RegistryDwords) ==

{{Status|warning}} These registry dwords are '''global''': they affect every NVIDIA GPU in the host. Do not use the
Gen2/P2P lines on a mixed rig (e.g. with an RTX 4080), or you force that card to Gen2 too.
{{Source|ybryany|2026-10-14|https://discord.com/channels/1518634379604136178/1518695289278566450/1559747855546187787}}

{| class="wikitable"
! Key !! Meaning !! Where it comes from
|-
| <code>RmForceEnableGen2=1</code> || The dword that enables PCIe Gen2 on the 170HX. The one that matters for Gen2. || cmpunlocker <code>cmp-pcie-gen2.conf</code>
|-
| <code>RMPcieLinkSpeed=0x1</code> || Gen2 link-speed bitfield (not "gen 1"). Shipped in the Gen2 conf. || cmpunlocker
|-
| <code>RMPcieLinkSpeed=0x5</code> || Gen3 link-speed bitfield used by the 10 GB Gen3 patch (not "gen 5"). || lixiangwuxian/170hx_tips
|-
| <code>CmpGen3=1</code> || Custom registry key read by the Gen3 patch; does nothing on a stock driver. || lixiangwuxian/170hx_tips
|-
| <code>ForceP2P=0x11</code> || Arms the mailbox [[P2P]] trap (Morrowmake fork / ropuls gist). || {{Source|68x0|2026-10-13|https://discord.com/channels/1518634379604136178/1518695289278566450/1559704654743474310}}
|-
| <code>RMForceStaticBar1=1</code> || Static BAR1 (ropuls gist, with the P2P set). || ropuls gist
|-
| <code>RMPcieP2PType=1;RMForceP2PType=1</code> || Force the P2P type (ropuls gist). || ropuls gist
|}

Two full lines in use:

<syntaxhighlight lang="text">
# cmpunlocker Gen2 (both cards)
options nvidia NVreg_RegistryDwords="RmForceEnableGen2=1;RMPcieLinkSpeed=0x1"

# Morrowmake P2P fork
options nvidia NVreg_RegistryDwords="RmForceEnableGen2=1;RMPcieLinkSpeed=0x1;ForceP2P=0x11"

# 10 GB Gen3 (lixiangwuxian/170hx_tips), with the patched module
options nvidia NVreg_RegistryDwords="RmForceEnableGen2=1;RMPcieLinkSpeed=0x5;CmpGen3=1" cmp_fuse_gen3=0

# ropuls gist (GLOBAL, 170HX-only rigs; forces all GPUs to Gen2)
options nvidia NVreg_RegistryDwords="RmForceEnableGen2=1;RMPcieLinkSpeed=0x1;RMForceStaticBar1=1;RMPcieP2PType=1;RMForceP2PType=1;ForceP2P=0x11"
</syntaxhighlight>

== Patched-module parameters (not stock) ==

These only exist on a patched <code>nvidia</code> module; check with
<code>modinfo -p nvidia | grep -E 'cmp_fuse|CmpGen3'</code>. Adding them to a stock driver does nothing.

{| class="wikitable"
! Parameter !! Meaning
|-
| <code>cmp_fuse_gen3=0</code> || Clear the Gen3-disabled fuse state at probe (10 GB Gen3). Set '''only''' this for Gen3; do not add <code>cmp_fuse_gpc=0</code>, <code>cmp_fuse_tpc*=0</code> or <code>cmp_fuse_flr=1</code>.
|-
| <code>cmp_fuse_bdf=0000:03:00.0</code> || Restrict the fuse override to one card.
|}

== asm64 fork installer flags (compile-time) ==

<code>--mclk-ndiv=N</code> (HBM clock = N x 27 MHz, baked into the module), <code>--mclk-timings=N</code> (-50..+50 %),
<code>--p2p</code>, <code>--no-gen2</code>, <code>--no-iommu</code>, <code>--no-persist</code>. {{Status|warning}}
A baked <code>--mclk-ndiv</code> makes 170tune refuse to tune; <code>--mclk-timings</code> <code>tCCD_L=3</code>
hard-hangs the controller (reboot to recover). See [[cmpunlocker forks]] and [[Cooling and power]].

== Related ==

[[Driver unlock]], [[Gen2 link retrain]], [[PCIe Gen3 on the 10 GB card]], [[P2P]], [[RIR fuse burn]],
[[Resizable BAR and BAR1 64 GB]], [[Tools]], [[Troubleshooting]].

{{ImportFooter}}
[[Category:Unlocks]]
[[Category:8 GB]]
[[Category:10 GB]]