Kernel 4.x (for example 4.19) load kernel su as kernel module

[ABC00012345]

Is that possible?
If i have the kernel source, can i compile the kernel module and load it on the running kernel?

[XNinety9]

Technically yes, practically it's not the route the project supports for 4.x.

What's possible: CONFIG_KSU is a tristate, so with your kernel source you can build it as kernelsu.ko (CONFIG_KSU=m). For a 4.19 kernel that has to be v0.9.5. Since v1.0, KernelSU dropped official non-GKI support, and v0.9.5 is the last version that builds on those kernels (see the archived Integrate for non-GKI devices guide and #1705). For the module to load, it must be built against the exact source and .config of the running kernel (same vermagic). The kernel needs CONFIG_MODULES and CONFIG_KPROBES (v0.9.5 hooks via kprobes), and it must not enforce module signatures, unless you can sign with the kernel's key.

Why it's still not the usual way:

• To insmod a module on a running system, you need root already. The official LKM mode gets around that by patching the ramdisk (init_boot/boot) so init loads the module early. That tooling targets GKI kernels (5.10+) and their KMIs, not a 4.19 vendor kernel.
• KernelSU needs to be active before most of userspace starts (manager detection, module mounting, the umount feature). Loaded late, a lot of it doesn't behave as intended. On < 5.9, the umount feature also needs path_umount backported, as the guide explains.

So for 4.19, the practical path is what the archived guide describes: integrate v0.9.5 into the kernel (CONFIG_KSU=y), via kprobes or the manual hooks, then build and flash that kernel. Since you have the source, that's the most reliable route. A loadable module only makes sense if you specifically want to avoid replacing the kernel, and then you'd have to build your own early-loading mechanism.

[ABC00012345]

Thanks for the reply. I successfully ported the kernelsu module (around version 3.25) to my device. I used an existing port for a similar device and made it compatible with my device. It loaded then successfully using temp root.
I will close this question now since the issue is resolved. Thanks again