/*===========================================================================*
* do_rt_set_rm *
*===========================================================================*/
PRIVATE int do_rt_set_rm(message *m_ptr, struct proc *rp)
{
struct proc *xp;
/* if rm_prio_policy equals PRIO_UNIQUE the priority of a
* process scheduled with RM should be unique. We will have to
* loop through the process table to check if there is no other process
* with this priority.
*/
if (rm_prio_policy == PRIO_UNIQUE) {
for (xp = BEG_PROC_ADDR; xp < END_PROC_ADDR; ++xp) {
if (xp->p_rts_flags != SLOT_FREE &&
is_rtp(xp) && xp->p_rt_priority == m_ptr->RM_PRIO) {
return (EINVAL);
}
}
}
if ( rp->p_rts_flags == 0) {
/* Should not happen normally.
* A process is runnable if p_rts_flags is zero.
* The process requesting to be real-time should be
* blocked waiting for a reply from PM
* and thus p_rts_flags should not be zero.
* Still we remove the process from the scheduling queue.
*/
lock_dequeue(rp);
}
/* Now we can change the process structure.
* First make sure this process will be recognized
* as a real-time process.
*/
rp->p_rt = 1;
/* Set the current and maximum priority to the
* real-time queue.
*/
rp->p_max_priority = rp->p_priority = RT_Q;
/* set the static priority */
rp->p_rt_priority = m_ptr->RM_PRIO;
if ( rp->p_rts_flags == 0) {
/* Should not happen normally.
* See above. Add process to the scheduling queue.
*/
lock_enqueue(rp);
}
return (OK);
}
/*===========================================================================*
* do_nice *
*===========================================================================*/
PUBLIC int do_nice(message *m_ptr)
{
/* Change process priority or stop the process. */
int proc_nr, pri, new_q ;
register struct proc *rp;
/* Extract the message parameters and do sanity checking. */
if(!isokendpt(m_ptr->PR_ENDPT, &proc_nr)) return EINVAL;
if (iskerneln(proc_nr)) return(EPERM);
pri = m_ptr->PR_PRIORITY;
rp = proc_addr(proc_nr);
if (is_rtp(rp)) return (EPERM); /* don't allow nice for RT processes */
if (pri == PRIO_STOP) {
/* Take process off the scheduling queues. */
lock_dequeue(rp);
rp->p_rts_flags |= NO_PRIORITY;
return(OK);
}
else if (pri >= PRIO_MIN && pri <= PRIO_MAX) {
/* The value passed in is currently between PRIO_MIN and PRIO_MAX.
* We have to scale this between MIN_USER_Q and MAX_USER_Q to match
* the kernel's scheduling queues.
*/
new_q = MAX_USER_Q + (pri-PRIO_MIN) * (MIN_USER_Q-MAX_USER_Q+1) /
(PRIO_MAX-PRIO_MIN+1);
if (new_q < MAX_USER_Q) new_q = MAX_USER_Q; /* shouldn't happen */
if (new_q > MIN_USER_Q) new_q = MIN_USER_Q; /* shouldn't happen */
if (new_q == RT_Q && !is_rtp(rp)) return (EINVAL); /* don't allow other processes in the RT queue */
/* Make sure the process is not running while changing its priority.
* Put the process back in its new queue if it is runnable.
*/
lock_dequeue(rp);
rp->p_max_priority = rp->p_priority = new_q;
if (! rp->p_rts_flags) lock_enqueue(rp);
return(OK);
}
return(EINVAL);
}
/*===========================================================================*
* do_quantum *
*===========================================================================*/
PUBLIC int do_quantum(message *m_ptr)
{
int proc_nr, quantum;
register struct proc *rp;
/* Individuo il numero del processo da modificare */
proc_nr = m_ptr->PR_PROC_NR ;
/* Il numero del processo non e` valido */
if (! isokprocn(proc_nr)) return(EINVAL);
/* Consento di modificare la dimensione del quanto solo nei processi utente */
if (iskerneln(proc_nr)) return(EPERM);
/* Nuova dimensione del quanto */
quantum = m_ptr->PR_QUANTUM;
/* Controllo che la sua dimensione rispetti i limiti consentiti */
if (quantum < MIN_QUANTUM_SIZE) {
kprintf("WARNING: quantum size exceeds MIN_QUANTUM_SIZE, it will be raised to %d ticks\n",MIN_QUANTUM_SIZE);
quantum = MIN_QUANTUM_SIZE;
}
else if (quantum > MAX_QUANTUM_SIZE) {
kprintf("WARNING: quantum size exceeds MAX_QUANTUM_SIZE, it will be lowered to %d ticks\n",MAX_QUANTUM_SIZE);
quantum = MAX_QUANTUM_SIZE;
}
/* Seleziono il processo da aggiornare */
rp = proc_addr(proc_nr);
/* Lo rimuovo dalla coda */
lock_dequeue(rp);
/* Aggiorno la dimensione del quanto */
rp->p_quantum_size = quantum;
/* Reinserisco il processo in coda */
if (! rp->p_rts_flags) lock_enqueue(rp);
return(OK);
}
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC void main()
{
/* Start the ball rolling. */
struct boot_image *ip; /* boot image pointer */
register struct proc *rp; /* process pointer */
register struct priv *sp; /* privilege structure pointer */
register int i, s;
int hdrindex; /* index to array of a.out headers */
phys_clicks text_base;
vir_clicks text_clicks, data_clicks;
reg_t ktsb; /* kernel task stack base */
struct exec e_hdr; /* for a copy of an a.out header */
/* Initialize the interrupt controller. */
intr_init(1);
/* Clear the process table. Anounce each slot as empty and set up mappings
* for proc_addr() and proc_nr() macros. Do the same for the table with
* privilege structures for the system processes.
*/
for (rp = BEG_PROC_ADDR, i = -NR_TASKS; rp < END_PROC_ADDR; ++rp, ++i) {
rp->p_rts_flags = SLOT_FREE; /* initialize free slot */
rp->p_nr = i; /* proc number from ptr */
(pproc_addr + NR_TASKS)[i] = rp; /* proc ptr from number */
}
for (sp = BEG_PRIV_ADDR, i = 0; sp < END_PRIV_ADDR; ++sp, ++i) {
sp->s_proc_nr = NONE; /* initialize as free */
sp->s_id = i; /* priv structure index */
ppriv_addr[i] = sp; /* priv ptr from number */
}
/* Set up proc table entries for processes in boot image. The stacks of the
* kernel tasks are initialized to an array in data space. The stacks
* of the servers have been added to the data segment by the monitor, so
* the stack pointer is set to the end of the data segment. All the
* processes are in low memory on the 8086. On the 386 only the kernel
* is in low memory, the rest is loaded in extended memory.
*/
/* Task stacks. */
ktsb = (reg_t) t_stack;
for (i=0; i < NR_BOOT_PROCS; ++i) {
ip = &image[i]; /* process' attributes */
rp = proc_addr(ip->proc_nr); /* get process pointer */
rp->p_max_priority = ip->priority; /* max scheduling priority */
rp->p_priority = ip->priority; /* current priority */
rp->p_quantum_size = ip->quantum; /* quantum size in ticks */
rp->p_ticks_left = ip->quantum; /* current credit */
strncpy(rp->p_name, ip->proc_name, P_NAME_LEN); /* set process name */
(void) get_priv(rp, (ip->flags & SYS_PROC)); /* assign structure */
priv(rp)->s_flags = ip->flags; /* process flags */
priv(rp)->s_trap_mask = ip->trap_mask; /* allowed traps */
priv(rp)->s_call_mask = ip->call_mask; /* kernel call mask */
priv(rp)->s_ipc_to.chunk[0] = ip->ipc_to; /* restrict targets */
if (iskerneln(proc_nr(rp))) { /* part of the kernel? */
if (ip->stksize > 0) { /* HARDWARE stack size is 0 */
rp->p_priv->s_stack_guard = (reg_t *) ktsb;
*rp->p_priv->s_stack_guard = STACK_GUARD;
}
ktsb += ip->stksize; /* point to high end of stack */
rp->p_reg.sp = ktsb; /* this task's initial stack ptr */
text_base = kinfo.code_base >> CLICK_SHIFT;
/* processes that are in the kernel */
hdrindex = 0; /* all use the first a.out header */
} else {
hdrindex = 1 + i-NR_TASKS; /* servers, drivers, INIT */
}
/* The bootstrap loader created an array of the a.out headers at
* absolute address 'aout'. Get one element to e_hdr.
*/
phys_copy(aout + hdrindex * A_MINHDR, vir2phys(&e_hdr),
(phys_bytes) A_MINHDR);
/* Convert addresses to clicks and build process memory map */
text_base = e_hdr.a_syms >> CLICK_SHIFT;
text_clicks = (e_hdr.a_text + CLICK_SIZE-1) >> CLICK_SHIFT;
if (!(e_hdr.a_flags & A_SEP)) text_clicks = 0; /* common I&D */
data_clicks = (e_hdr.a_total + CLICK_SIZE-1) >> CLICK_SHIFT;
rp->p_memmap[T].mem_phys = text_base;
rp->p_memmap[T].mem_len = text_clicks;
rp->p_memmap[D].mem_phys = text_base + text_clicks;
rp->p_memmap[D].mem_len = data_clicks;
rp->p_memmap[S].mem_phys = text_base + text_clicks + data_clicks;
rp->p_memmap[S].mem_vir = data_clicks; /* empty - stack is in data */
/* Set initial register values. The processor status word for tasks
* is different from that of other processes because tasks can
* access I/O; this is not allowed to less-privileged processes
*/
rp->p_reg.pc = (reg_t) ip->initial_pc;
rp->p_reg.psw = (iskernelp(rp)) ? INIT_TASK_PSW : INIT_PSW;
/* Initialize the server stack pointer. Take it down one word
* to give crtso.s something to use as "argc".
*/
if (isusern(proc_nr(rp))) { /* user-space process? */
rp->p_reg.sp = (rp->p_memmap[S].mem_vir +
rp->p_memmap[S].mem_len) << CLICK_SHIFT;
rp->p_reg.sp -= sizeof(reg_t);
}
/* Set ready. The HARDWARE task is never ready. */
if (rp->p_nr != HARDWARE) {
rp->p_rts_flags = 0; /* runnable if no flags */
lock_enqueue(rp); /* add to scheduling queues */
} else {
rp->p_rts_flags = NO_MAP; /* prevent from running */
}
/* Code and data segments must be allocated in protected mode. */
alloc_segments(rp);
}
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC void main()
{
/* Start the ball rolling. */
struct boot_image *ip; /* boot image pointer */
register struct proc *rp; /* process pointer */
register struct priv *sp; /* privilege structure pointer */
register int i, s;
// a.out 头部数组的索引.
int hdrindex; /* index to array of a.out headers */
phys_clicks text_base;
vir_clicks text_clicks, data_clicks;
// 内核任务栈的基地址(低端)
reg_t ktsb; /* kernel task stack base */
// 用来放置 a.out 头部的一个副本.
struct exec e_hdr; /* for a copy of an a.out header */
/* Initialize the interrupt controller. */
// 初始化 8259 中断控制器芯片.
intr_init(1);
/* Clear the process table. Anounce each slot as empty and set up mappings
* for proc_addr() and proc_nr() macros. Do the same for the table with
* privilege structures for the system processes.
*/
// 初如化进程表与进程指针表.
// BEG_PROC_ADDR: 进程表地址;
for (rp = BEG_PROC_ADDR, i = -NR_TASKS; rp < END_PROC_ADDR; ++rp, ++i) {
// 将进程表中每一项都设置为空闲.
rp->p_rts_flags = SLOT_FREE; /* initialize free slot */
// 进程号, i 的初值为 -NR_TASKS, 可见系统任务拥有负的进程号
rp->p_nr = i; /* proc number from ptr */
// 建立进程数组与进程指针数组之间的映射关系
(pproc_addr + NR_TASKS)[i] = rp; /* proc ptr from number */
}
// 初始化优先级表
for (sp = BEG_PRIV_ADDR, i = 0; sp < END_PRIV_ADDR; ++sp, ++i) {
sp->s_proc_nr = NONE; /* initialize as free */
sp->s_id = i; /* priv structure index */
// 建立特权级表与特权级指针表之间的映射关系
ppriv_addr[i] = sp; /* priv ptr from number */
}
/* Set up proc table entries for tasks and servers. The stacks of the
* kernel tasks are initialized to an array in data space. The stacks
* of the servers have been added to the data segment by the monitor, so
* the stack pointer is set to the end of the data segment. All the
* processes are in low memory on the 8086. On the 386 only the kernel
* is in low memory, the rest is loaded in extended memory.
*/
/*
* 为任务和服务进程设置进程表项. 内核任务的栈被初始化成一个在数据空间中的
* 数组. 服务进程的栈已经由控制器添加到数据段中, 所有它们的栈指针开始时
* 指向数据段的末尾. 所有的进程都在 8086 的低内存. 对于 386, 只有内核在
* 低内存, 剩下的都在扩展内存中.
*/
/* Task stacks. */
/* 任务栈 */
ktsb = (reg_t) t_stack;
// 为那些包含在系统引导映像文件中的程序分配进程表项.
for (i=0; i < NR_BOOT_PROCS; ++i) {
ip = &image[i]; /* process' attributes */
// 获取进程指针
rp = proc_addr(ip->proc_nr); /* get process pointer */
// 最大调度优先级
rp->p_max_priority = ip->priority; /* max scheduling priority */
// 当前调度优先级
rp->p_priority = ip->priority; /* current priority */
// 时间片原子值
rp->p_quantum_size = ip->quantum; /* quantum size in ticks */
// 剩余时间片
rp->p_ticks_left = ip->quantum; /* current credit */
// 将程序名复制到进程表项中
strncpy(rp->p_name, ip->proc_name, P_NAME_LEN); /* set process name */
// 为进程分配一个特权级结构体, 即 从系统特权级表中分配一项
(void) get_priv(rp, (ip->flags & SYS_PROC)); /* assign structure */
// 初始化特权级结构体的标志.
priv(rp)->s_flags = ip->flags; /* process flags */
// 初始化特权级结构体的 允许的系统调用陷井
priv(rp)->s_trap_mask = ip->trap_mask; /* allowed traps */
priv(rp)->s_call_mask = ip->call_mask; /* kernel call mask */
// 初始化进程的消息发送位图
priv(rp)->s_ipc_to.chunk[0] = ip->ipc_to; /* restrict targets */
// 如果进程是内核任务
if (iskerneln(proc_nr(rp))) { /* part of the kernel? */
// 如果进程的栈大小大于 0, 设置进程的栈警戒字,
if (ip->stksize > 0) { /* HARDWARE stack size is 0 */
// 设置内核任务栈警戒字指针.
rp->p_priv->s_stack_guard = (reg_t *) ktsb;
// 指针运算符(->) 要比取值运行符 (*) 的优先级要高.
// 等价于:
// *(rp->p_priv->s_stack_guard) = STACK_GUARD
// 效果是在栈的最顶端(在低地址)放置一个特殊值,
// 这个值就是栈警戒字.
*rp->p_priv->s_stack_guard = STACK_GUARD;
}
ktsb += ip->stksize; /* point to high end of stack */
// 初始进程的栈指针
rp->p_reg.sp = ktsb; /* this task's initial stack ptr */
// kinfo ???
// 内核代码的基地址右移 CLICK_SHIFT 位, 赋给 text_base.
text_base = kinfo.code_base >> CLICK_SHIFT;
/* processes that are in the kernel */
// 内核任务使用同一个 a.out 头部信息
hdrindex = 0; /* all use the first a.out header */
} else {
// 非内核任务, 计算它的 a.out 头部数组索引, 因为 0 号项
// 留给了内核任务, 所以需 加 1.
hdrindex = 1 + i-NR_TASKS; /* servers, drivers, INIT */
}
/* The bootstrap loader created an array of the a.out headers at
* absolute address 'aout'. Get one element to e_hdr.
*/
/*
* 引导加载程序会在绝对地址 'aout' 处放置一个 a.out 头部数组.
* 从中取一项复制到 e_hdr.
*/
phys_copy(aout + hdrindex * A_MINHDR, vir2phys(&e_hdr),
(phys_bytes) A_MINHDR);
/* Convert addresses to clicks and build process memory map */
/* 将地址转换为以 click 为单位, 并建立进程内存映射 */
// 既然这里要设置 text_base, 那 146 行附近的
// text_base = kinfo.code_base >> CLICK_SHIFT;
// 岂不是多余的??
// 将 a.out 头部的符号表大小右移 CLICK_SHIFT 位,赋给 text_base.
text_base = e_hdr.a_syms >> CLICK_SHIFT;
// 计算程序文本段大小, 以 click 为单位, 上取整.
text_clicks = (e_hdr.a_text + CLICK_SIZE-1) >> CLICK_SHIFT;
// 如果 a.out 头部指明它的 I/D 是合并的 ???
if (!(e_hdr.a_flags & A_SEP)) text_clicks = 0; /* common I&D */
// 计算程序占用的内存量, 以 click 为单位, 上取整.
data_clicks = (e_hdr.a_total + CLICK_SIZE-1) >> CLICK_SHIFT;
// 初始化进程的内存映射数据结构
rp->p_memmap[T].mem_phys = text_base;
rp->p_memmap[T].mem_len = text_clicks;
rp->p_memmap[D].mem_phys = text_base + text_clicks;
rp->p_memmap[D].mem_len = data_clicks;
rp->p_memmap[S].mem_phys = text_base + text_clicks + data_clicks;
rp->p_memmap[S].mem_vir = data_clicks; /* empty - stack is in data */
/* Set initial register values. The processor status word for tasks
* is different from that of other processes because tasks can
* access I/O; this is not allowed to less-privileged processes
*/
/*
* 设置寄存器的初始值. 与其他进程相比, 内核任务的处理器状态字
* 稍有不同, 因为内核任务可以访问 I/O; 而对于非特权进来来说, 这是不
* 允许的.
*/
// 初始化进程的 PC 和 processor status word.
rp->p_reg.pc = (reg_t) ip->initial_pc;
rp->p_reg.psw = (iskernelp(rp)) ? INIT_TASK_PSW : INIT_PSW;
/* Initialize the server stack pointer. Take it down one word
* to give crtso.s something to use as "argc".
*/
/*
* 初始化服务器进程的栈指针. 下移一个字的空间, 使得 crtso.s 有
* 空间放置 "argc".
*/
if (isusern(proc_nr(rp))) { /* user-space process? */
rp->p_reg.sp = (rp->p_memmap[S].mem_vir +
rp->p_memmap[S].mem_len) << CLICK_SHIFT;
rp->p_reg.sp -= sizeof(reg_t);
}
/* Set ready. The HARDWARE task is never ready. */
if (rp->p_nr != HARDWARE) {
// 如果进程不是 HARDWARE, 清空进程标志, 并加入调度队列.
rp->p_rts_flags = 0; /* runnable if no flags */
lock_enqueue(rp); /* add to scheduling queues */
} else {
// 对于 HARDWARE 任务, 则阻止其运行. ???
rp->p_rts_flags = NO_MAP; /* prevent from running */
}
/* Code and data segments must be allocated in protected mode. */
/* 数据与代码段必须在保护模式下分配 */
alloc_segments(rp);
}