diff options
| -rw-r--r-- | include/fbos/init.h | 6 | ||||
| -rw-r--r-- | include/fbos/sched.h | 23 | ||||
| -rw-r--r-- | kernel/main.c | 17 | ||||
| -rw-r--r-- | kernel/trap.c | 5 |
4 files changed, 30 insertions, 21 deletions
diff --git a/include/fbos/init.h b/include/fbos/init.h index a3cc16f..f253645 100644 --- a/include/fbos/init.h +++ b/include/fbos/init.h @@ -50,7 +50,11 @@ void extract_initrd(const unsigned char *const base_addr, uint64_t size, // Setup the interrupt vectors and the SBI timer. void setup_interrupts(void); -// The entry point for the kernel. +/* + * This is the main entry point of the kernel after head.S is done. This + * function can (and will) assume that everything has been reset and that we can + * start the whole thing. + */ void start_kernel(void *dtb); #endif /* __FBOS_INIT_H */ diff --git a/include/fbos/sched.h b/include/fbos/sched.h index ced620c..23763d3 100644 --- a/include/fbos/sched.h +++ b/include/fbos/sched.h @@ -24,15 +24,28 @@ struct task_struct { const void *entry_addr; }; -// Instantiated in kernel/main.c. +/* + * Stack to be used by our processes, which is initialized in head.S. + * "Blasphemy!" I hear you say. "How dare you use the same stack for kernel and + * user space?" It's not like this is some sort of utopian system in which + * everyone shares everything, but since this stupidly simple kernel does not\ + * even bother to implement paging nor any other memory protection of any kind, + * it's not like separating stacks for each process and kernel space would make + * much of a difference. Hence, let's keep it simple and have the same stack + * everwhere. + * + * Instantiated in kernel/main.c. + */ extern uint64_t stack[]; -// Tasks available on this kernel. +// Tasks available on this kernel. Instantiated in kernel/main.c extern struct task_struct tasks[4]; -// Prepare for switching to the given task. Note that this will not actually -// jump into the given task, but it will prepare the relevant registers before -// performing the actual jump. +/* + * Prepare for switching to the given task. Note that this will not actually + * jump into the given task, but it will prepare the relevant registers before + * performing the actual jump. + */ __kernel __always_inline void prepare_switch_to(int task_id) { register struct task_struct *current asm("tp"); diff --git a/kernel/main.c b/kernel/main.c index 822d638..41619d6 100644 --- a/kernel/main.c +++ b/kernel/main.c @@ -11,18 +11,10 @@ atomic32_t hart_lottery __section(".sdata"); uint32_t hart_id; -// Stack to be used by our processes, which is initialized in head.S. -// "Blasphemy!" I hear you say. "How dare you use the same stack for kernel and -// user space?" It's not like this is some sort of utopian system in which -// everyone shares everything, but since this stupidly simple kernel does not -// even bother to implement paging nor any other memory protection of any kind, -// it's not like separating stacks for each process and kernel space would make -// much of a difference. Hence, let's keep it simple and have the same stack -// everwhere. +// Defined in fbos/sched.h. uint64_t stack[STACK_SIZE / sizeof(uint64_t)]; -// Initialize the list of structs by providing a fixed stack address and empty -// values everywhere else. +// Defined in fbos/sched.h. struct task_struct tasks[4] = { [TASK_INIT] = { .name = "init", .entry_addr = nullptr, }, [TASK_FIZZ] = { .name = "fizz", .entry_addr = nullptr, }, @@ -38,11 +30,6 @@ struct dt_info info = { .initrd_end = 0, }; -/* - * This is the main entry point of the kernel after head.S is done. This - * function can (and will) assume that everything has been reset and that we can - * start the whole thing. - */ __noreturn __kernel void start_kernel(void *dtb) { printk("Welcome to FizzBuzz OS!\n"); diff --git a/kernel/trap.c b/kernel/trap.c index 29f1c21..855b048 100644 --- a/kernel/trap.c +++ b/kernel/trap.c @@ -39,6 +39,11 @@ __kernel void time_out_in_one_second(void) } } +/* + * Exception handler. For this kernel, it only ensures that the 'write' system + * call is the one responsible for this exception and handles it; otherwise it + * will die. + */ __kernel __always_inline void exception_handler(uint64_t cause) { register char *message asm("a0"); |