Zagitta/gpu-unlock

Source: https://github.com/Zagitta/gpu-unlock

GPU unlock 1.0.0 packaging candidate

This Linux kernel module combines the CMP unlocker’s V67/PLM technique with the pre-driver timing of the UEFI approach. It runs the unlock, writes the speed selectors (SS0 0x88888888, which selects the full BF16 rate, and the 4-bit SS1 0x8, whose effect is untested) and performs FLR before the unmodified NVIDIA driver binds the card. It is neither a UEFI application nor a patched NVIDIA driver.

The observed result is GPU1, an RTX 3090 at 0000:21:00.0, on the main CachyOS 7.2.8-1-cachyos kernel with NVIDIA 615.71.09. GPU0 at 0000:01:00.0 was an unmodified control. Other RTX 3090 boards and environments have not been verified. GeForce and CMP GA102/GA104 PCI device IDs are accepted; professional RTX A-series and data-centre parts are not. No GA104 card and no GA102 card other than the RTX 3090 has been tested; the firmware and V67 image are the GA102 ones. Other chips are rejected.

Local build

Every build downloads the pinned NVIDIA/CachyOS inputs over HTTPS, checks their SHA-256, and generates firmware only in the build directory and the binary package. All three formats install through the same make install-* targets. Packages are built from the committed HEAD.

Build, install build dependencies, and install the packages in one step (asks for your sudo password):

make install-arch   # makepkg -sif
make install-deb    # apt-get build-dep, dpkg-buildpackage, apt-get install
make install-rpm    # dnf builddep, rpmbuild, dnf install

make arch, make deb and make rpm only build. Debian and RPM packages go to build/deb and build/rpm. The NVIDIA inputs are cached in ~/.cache/gpu-unlock/inputs (make inputs; override with INPUTS=). dpkg-buildpackage itself never uses the network, so a clean-chroot build (sbuild or pbuilder) needs GPU_UNLOCK_INPUTS pointing at that cache. The make dist archive, the Debian source package and the .nosrc.rpm contain no NVIDIA archives or generated firmware.

Boot flow and opt-in

The packages put gpu_unlock and its firmware in the initramfs and load it there, before nvidia can bind a card:

• mkinitcpio: /etc/mkinitcpio.conf.d/zz-gpu-unlock.conf inserts gpu_unlock right before nvidia in MODULES, so a display card is blank for as short a time as possible. Without nvidia in the image, it goes last and still runs before an nvidia loaded from the root filesystem. Images are rebuilt on install. mkinitcpio ignores drop-ins for an image built with -c <config> or a preset _config; put gpu_unlock right before nvidia in that config’s MODULES yourself.
• initramfs-tools: /usr/share/initramfs-tools/modules.d/gpu-unlock.conf.
• dracut: /usr/lib/dracut/dracut.conf.d/gpu-unlock.conf.

There is no softdep nvidia pre: rule: kmod honours only the first softdep nvidia line it reads, so other packages’ rules (nvidia-utils, gddr6_hwmon) would silently override it, or it would override theirs.

The module does nothing unless the kernel command line opts in:

gpu_unlock.targets=all                          # every unbound GA102/GA104 card
gpu_unlock.targets=0000:21:00.0                 # only these cards
gpu_unlock.targets=0000:21:00.0,0000:22:00.0    # comma-separated

Addresses are full PCI names as lspci -D prints them (hex digits in either case), independent of GPU numbering and display role. An entry that is not a GA102/GA104 card, including all mixed with addresses, is logged and ignored. The cards are unlocked concurrently, about a second in all however many there are, and each on its own: a card that is already bound, powered down or bus mastering is skipped. Then nvidia loads and binds every card as usual.

The display card works too. Its firmware framebuffer (the boot console and Plymouth) keeps running while the unlock’s firmware steps run, and is removed just before the card’s reset, as nvidia-drm would do a moment later anyway. Its screen is blank from that reset until nvidia-drm takes over.

The unlock needs a cold card: power the machine off rather than rebooting. Warm reboots are not supported; with the option set, the unlock is expected to fail and leave the card as it was. Loading the module by hand after boot does nothing to a card that nvidia has bound. A card that a driver already used this power cycle is refused before any firmware runs (card already initialised since power on).

Check the result with:

journalctl -k -b | grep gpu_unlock
lspci -nnk -s 0000:21:00.0

To stop unlocking, remove gpu_unlock.targets= from the kernel command line; for a one-off boot, delete it in the bootloader’s edit screen. Removing the packages also removes the module and the initramfs drop-ins.

If the firmware on a card never stops, the module logs it and keeps the DMA buffers that firmware may still use until the next power off. Power off before trying again.

The kernel module and local packaging are GPL-2.0-only. The generated payload derives from the pinned CMP reference; NVIDIA firmware remains under its own terms. See firmware/NOTICE.md and licenses/ for attribution and notices.

Support me

Help me buy more GPUs <3

https://buymeacoffee.com/zagitta ETH: 0xf4eee937937f92038D70B16AbD7736D8a53a1c5c BTC: bc1qwpkwp70fn76z3s4kg2l9y3j4kst95twcznuugf SOL: 8Rih6HY7V4LcdjYHz4iSffT4fTniqw5CACaBigSVxNYu