linux_cachyos-lto: adopt nixpkgs#402198

[PedroHLC]

Blocked by NixOS/nixpkgs#402198

🐟 What?

Simplifies the entire build setup by relying on Nixpkgs changes.

🎣 Why?

Hopefully fixes kernel modules.

[ccicnce113424]

NixOS/nixpkgs#402198 has been merged. Is this PR ready?

[PedroHLC]

NixOS/nixpkgs#402198 has been merged. Is this PR ready?

Merged to staging, it still needs to hit master and deploy to nixos-unstable before we can use it.

But I already tested it, and as it is now, it doesn't mass-fix the modules. I'll have to override them with fixes, but it opens the door to fixing them in Nixpkgs. E.g., we can open PRs to fix pkgsLLVM.linuxPackages_latest.xpadone and that would fix it here too.

[ccicnce113424]

I tried to build pkgsLLVM.linuxPackages_latest.xpad-noone and failed.
Blocked by NixOS/nixpkgs#429009.
https://github.com/ccicnce113424/nixpkgs-review-gha/actions/runs/16577172341/job/46884218620

[ccicnce113424]

Blocked by NixOS/nixpkgs#429745 now.

[ccicnce113424]

Link related issue here: NixOS/nixpkgs#321667

[ccicnce113424]

But I already tested it, and as it is now, it doesn't mass-fix the modules. I'll have to override them with fixes, but it opens the door to fixing them in Nixpkgs.

The compiler is configured using makeFlags in NixOS/nixpkgs#402198. The fix is pretty simple, what we need to do is set makeFlags = kernelModuleMakeFlags;. See NixOS/nixpkgs#430035.

[PedroHLC]

Next nixos-unstable release, which will include NixOS/nixpkgs#402198, I might move us to a fork with NixOS/nixpkgs#429745 and NixOS/nixpkgs#430035 applied.

CachyOS already defaults for LTO, and I really need to catch up. -lto will be the new mainline and I'll introduce -gcc for the old folks yelling at clouds.

[PedroHLC]

This testing is with nixos-unstable-small.

[PedroHLC]

What built successfully:

acer-wmi-battery
acpi_call
ajantv2
akvcam
amneziawg
asus-ec-sensors
batman_adv
bbswitch
cpupower
cryptodev
ddcci-driver
dpdk-kmods
facetimehd
fanout
framework-laptop-kmod
gasket
gcadapter-oc-kmod
hid-t150
hid-tmff2
hpuefi-mod
hyperv-daemons
iio-utils
ipu6-drivers
it87
jool
kvmfr
lenovo-legion-module
liquidtux
msi-ec
mstflint_access
nct6687d
new-lg4ff
nullfs
nxp-pn5xx
ply
qc71_laptop
r8125
rtl8821ce
rtw88
sheep-net
system76-io
system76-io
system76-power
tmon
trelay
tsme-test
tt-kmd
tuxedo-drivers
universal-pidff
usbip
v4l2loopback
veikk-linux-driver
vendor-reset
vhba
virtio_vmmci
xone
xpad-noone

From these, 16 built for the first time in this repo's history. Thanks for the help RossComputerGuy, alyssais, and @ccicnce113424!

Now the ones failing (but not failing on GCC 6.16 kernel as well) are:

amdgpu-i2c
bcc
bpftrace
ch9344
corefreq
dpdk
ecapture
ena
mm-tools
nvidia_dc
nvidia_x11
nvidia_x11_beta
nvidia_x11_beta_open
nvidia_x11_latest
nvidia_x11_latest_open
nvidia_x11_legacy535
nvidia_x11_production_open
oci-seccomp-bpf-hook
odp-dpdk
openafs
openrazer
opensnitch-ebpf
perf
pktgen
ryzen-smu
system76-acpi
system76-scheduler
systemtap
tp_smapi
turbostat
v86d
virtualbox
virtualboxGuestAdditions
vmware
x86_energy_perf_policy
xpadneo
zenpower
zfs_*

But now, these should be fixed in Nixpkgs.

[ccicnce113424]

Test NVIDIA with this PR: NixOS/nixpkgs#440075