Universal Kernal Hook

[kh2k4]

I was wondering if the kernal could be hooked instead of a ELF loaded into the EE this way we wouldn't need to make mastercodes for mutitple ELF games or demo discs, KERMIT using the following to hook the Kernal

SceDeci2Poll - Used for host communication through usb cable I think.
SifSetReg
V_COMMON
Idle Loop

sorry if i'm covering old ground with this, I think Gtlcpimp brought it up before, is that what is used to hook CL-LiveDebug v3? is the method used on the PS1 cheat devices also? I don't remember any of them requiring mastercodes to enabled codes.

[Gtlcpimp]

Memory address: 0x800002FC
MIPS Instruction at address: jalr k0

When a "Syscall" instruction is executed, the EE executes a function in the kernel to operate the system event. The jump and link register instruction at the memory address above is what jumps the EE to the calculated system function.

Consider it the universal kernel hook, since it remains the same within every kernel version on every PS2 model. If you use it, you MUST preserve all registers AND continue the jump to the "Syscall address" (which is in register k0 obviously). You could, however, use it to operate a custom "Syscall" rather than letting it perform the kernel's original "Syscall". You just have to set a filter.

Yes this is what hooks LDv3, along with the cheat devices I wrote.

[kh2k4]

So I use
900002fc 0840f809

[Gtlcpimp]

No, you cannot use it in a master code setup. You have to manually write the hook.