Changes between Version 3 and Version 4 of boot_loader

Timestamp:

Nov 5, 2014, 4:36:31 PM (10 years ago)

Author:

alain

Comment:

--

boot_loader

@@ -1 @@
-= GIET_VM / Boot-Loader =
+= GIET_VM / Boot Procedure =
 
+== __Phase 0 : Reset__ ==
+
+This phase is executed in case of hard reset : all processors execute the ''reset'' code (also called ''preloader'' code) stored in the external ROM.
+Processor (0,0,0) load the GIET_VM boot-loader code from the external disk (or any other mass storage peripheral), to the physical memory of cluster(0,0).
+This ''reset'' code is generic. It is entirely defined by the target hardware architecture, and can be used to boot any operating system.  
+All other processors initialize their private interrupt controller, to be able to receive an inter-processor interrupt (WTI), and enter ''wait_state'' in low-power mode.
+
+== __Phase 1 : Boot__ ==
+
+In this this phase the GIET_VM boot-loader is executed by processor (0,0,0), while other processors are in wait state.
 The GIET-VM boot-loader is defined in the [source:soft/giet_vm/giet_boot/boot.c boot.c] file.
-
-The ''boot_init()'' function makes the initialisation in two steps:
- 
-== __Sequencial step__ ==
-
-The first step executed by proc[0][0][0], while other processors are in wait state.
+The main steps are the following:
 
 === void '''boot_pmem_init()''' ===
@@ -23 +28 @@
 on the cluster-coordinates: for the kernel code, a given virtual address is mapped to different physical addresses, depending on the cluster coordinates.
 
- 
-
-
 === '''boot_schedulers init()''' ===
 This function makes the schedulers initialisation, as specified in the mapping, with the following principles.
@@ -32 +34 @@
  * The allocation of task to processors is fully static (no task migration).
  * One single processor cannot schedule more than 14 tasks.
- s One scheduler occupies 8 Kbytes. The user
- * Peripherals initialisation : ''boot_peripherals_init()''
- * Kernel & application code loading : ''boot_elf_load()''
- * Start all other processors
+ One scheduler occupies 8 Kbytes, and contains the contexts of all tasks allocated to the processor (256 bytes per task).
+ 
+=== '''boot_peripherals_init()''' ===
+This function makes the external peripherals and coprocessors initialisation. 
 
-== __Parallel step__ ==
 
-This second step is executed in parallel by all processors:
- * CP0_SCHED register initialisation
- * MMU Activation 
- * Status Register Initialisation (to use the GIET_VM exception handler).
- * Jump to ''kernel_init()'' 
+=== '''''boot_elf_load()''' ===
+This function load into memory the kernel code (''kernel.elf'' file), and the user code for all applications specified in the mapping.
+
+
+Finally, processor(0,0,0) starts all other processors, using an inter-processor interrupt (WTI).
+Each processor initializes its own CP0_SCHED register, its own CP2_MODE register to activates its MMU, its own CP0_SR register to use the GIET_VM exception handler, and jumps
+to the ''kernel_init()''  function.
+
+== __Phase 2__ ==
+
+