GIET_VM / Kernel Initialisation

The kernel_init()​ function completes the system initialisation, that has been done by the boot-loader running on processor[0,0,0]. This kernel_init() function is executed sequencially by all processors.

It makes the following assuptions, regarding the work done by the boot-loader:

• The page tables associated to the various vspaces have been build in physical memory.
• All schedulers (including all task contexts) have been initialised.
• For each task, the page table virtual address is stored in the CTX_PTAB slot.
• For each task, the page table physical address is stored in the CTX_PTPR slots.
• The CP0_SCHED register of each processor contains a pointer on its private scheduler (virtual address).
• The CP2_PTPR register contains a pointer on the page table of vspace[0] (physical address>>13).
• For all processors, the MMU is activated (CP2_MODE contains 0xF).

Each processor performs the following actions:

1. contribute to _schedulers_paddr[] array initialisation.
2. contribute to _ptabs_paddr[] and _ptabs_vaddr arrays initialisation.
3. completes task context initialisation for each allocated task.
4. compute and set the XCU mask for its private XCU channel.
5. initialise its private TICK timer (if tasks > 0)
6. initialise the "idle" task context in its private scheduler
7. initialise SP, SR, PTPR, EPC registers and jump to user code with an eret.

This kernel_init code must be loaded in the .kinit section, in order to control the seg_kinit_base value that is used by the boot code to jump into kernel code.