[kernel] Dynamically allocate task array from bootopts

elks/arch/i86/boot/crt0.S

@@ -1,5 +1,4 @@
 #include <linuxmt/config.h>
-#include <arch/asm-offsets.h>
 
 //	Assembler boot strap hooks. This is called by setup
 
@@ -42,11 +41,11 @@ _start:
 	mov	%cs,kernel_cs
 	mov	%ds,kernel_ds
 
-// Set SS:SP to task[0] kernel stack area
+// Set SS:SP to kernel interrupt stack for temporary use
 
 	mov	%ds,%ax
 	mov	%ax,%ss		// SS=ES=DS
-	mov	$task + TASK_USER_AX,%sp
+	mov	$istack,%sp
 
 	call	start_kernel	// fall through into breakpoint if returns
 
@@ -81,7 +80,7 @@ early_putchar:
 	.global _endbss
 	.extern	kernel_cs
 	.extern	kernel_ds
-	.extern task
+	.extern	istack
 
 _endtext:
 	.word	0

elks/arch/i86/drivers/char/mem.c

@@ -230,6 +230,9 @@ int kmem_ioctl(struct inode *inode, struct file *file, int cmd, char *arg)
     case MEM_GETTASK:
 	retword = (unsigned short)task;
 	break;
+    case MEM_GETMAXTASKS:
+	retword = max_tasks;
+	break;
     case MEM_GETCS:
 	retword = kernel_cs;
 	break;

elks/arch/i86/kernel/irqtab.S

@@ -362,9 +362,9 @@ restore_regs:
 	iret
 
 /*
- *	tswitch();
+ *	tswitch()
  *
- *	This function can only be called with SS=DS=ES=kernel DS and
+ *	This function can only be called with SS=DS=kernel DS and
  *	CS=kernel CS. SS:SP is the relevant kernel stack. Thus we don't need
  *	to arse about with segment registers. The kernel isn't relocating.
  *
@@ -389,6 +389,13 @@ tswitch:
 	pop	%bp		// BP of schedule()
 	ret
 
+// setsp(void *sp) - set stack pointer
+	.global setsp
+setsp:
+	pop	%bx		// return address
+	pop	%ax
+	mov	%ax,%sp
+	jmp	*%bx
 
 // Halt - wait for next interrupt to save CPU power
 	.global idle_halt
@@ -399,6 +406,7 @@ idle_halt:
 	.data
 	.global	intr_count
 	.global	endistack
+	.global	istack
 	.extern	current
 	.extern	previous
 

elks/fs/exec.c

@@ -161,7 +161,7 @@ int sys_execve(const char *filename, char *sptr, size_t slen)
 	    seg_code = currentp->mm.seg_code;
 	    break;
 	}
-    } while (++currentp < &task[MAX_TASKS]);
+    } while (++currentp < &task[max_tasks]);
 
     /* Read the header */
     currentp = current;

elks/fs/namei.c

@@ -42,7 +42,7 @@ int permission(register struct inode *inode, int mask)
         do {
             if (p->state <= TASK_STOPPED && (p->t_inode == inode))
                 return -EBUSY;
-        } while (++p < &task[MAX_TASKS]);
+        } while (++p < &task[max_tasks]);
     }
     if ((mask & MAY_WRITE) && IS_RDONLY(inode) &&
         !S_ISCHR(inode->i_mode) && !S_ISBLK(inode->i_mode)) /* allow writable devices*/

elks/include/linuxmt/config.h

@@ -30,11 +30,12 @@
 #define UTS_MACHINE             "ibmpc i8086"
 
 /* The following can be set for minimal systems or for QEMU emulation testing:
- * 10 buffers (@20 = 200), 2 ttyq (@80 = 160), 4k L1 cache, 512 heap free = ~4968.
- * Use buf=10 cache=4 in /bootopts
+ * 10 buffers (@20 = 200), 2 ttyq (@80 = 160), 4k L1 cache, 512 heap free,
+ * 10 tasks (@876 = 8760) = ~13728.
+ * Use buf=10 cache=4 task=10 in /bootopts
  */
 #if defined(CONFIG_HW_MK88)
-#define SETUP_HEAPSIZE            4968    /* force kernel heap size */
+#define SETUP_HEAPSIZE            13728         /* force kernel heap size */
 #endif
 //#undef SETUP_MEM_KBYTES
 //#define SETUP_MEM_KBYTES        256     /* force available memory in 1K bytes */

elks/include/linuxmt/heap.h

@@ -18,7 +18,7 @@
 #define HEAP_TAG_SEG     0x01
 #define HEAP_TAG_BUF     0x02
 #define HEAP_TAG_TTY     0x03
-#define HEAP_TAG_INTHAND 0x04   /* unused */
+#define HEAP_TAG_TASK    0x04
 #define HEAP_TAG_BUFHEAD 0x05
 #define HEAP_TAG_PIPE    0x06
 

elks/include/linuxmt/mem.h

@@ -9,6 +9,7 @@
 #define MEM_GETHEAP	7
 #define MEM_GETUPTIME	8
 #define MEM_GETFARTEXT  9
+#define MEM_GETMAXTASKS 10
 
 struct mem_usage {
 	unsigned int free_memory;

elks/include/linuxmt/sched.h

@@ -110,7 +110,10 @@ struct task_struct {
 /* We use typedefs to avoid using struct foobar (*) */
 typedef struct task_struct __task, *__ptask;
 
-extern __task task[MAX_TASKS];
+extern __task *task;
+extern __task *next_task_slot;
+extern int max_tasks;
+extern int task_slots_unused;
 
 extern volatile jiff_t jiffies; /* ticks updated by the timer interrupt*/
 extern __ptask current;
@@ -125,7 +128,7 @@ extern time_t current_time(void);
 #define time_after(a,b)         (((long)(b) - (long)(a) < 0))
 
 #define for_each_task(p) \
-        for (p = &task[0] ; p!=&task[MAX_TASKS]; p++ )
+        for (p = &task[0] ; p!=&task[max_tasks]; p++ )
 
 /* Scheduling and sleeping function prototypes */
 
@@ -168,6 +171,7 @@ extern unsigned int get_ustack(struct task_struct *,int);
 extern void put_ustack(register struct task_struct *,int,int);
 
 extern void tswitch(void);
+extern void setsp(void *);
 extern int run_init_process(const char *cmd);
 extern int run_init_process_sptr(const char *cmd, char *sptr, int slen);
 extern void ret_from_syscall(void);

elks/init/main.c

@@ -13,6 +13,7 @@
 #include <linuxmt/netstat.h>
 #include <linuxmt/trace.h>
 #include <linuxmt/devnum.h>
+#include <linuxmt/heap.h>
 #include <arch/system.h>
 #include <arch/segment.h>
 #include <arch/ports.h>
@@ -45,6 +46,7 @@ __u16 kernel_cs, kernel_ds;
 int tracing;
 int nr_ext_bufs, nr_xms_bufs, nr_map_bufs;
 static int boot_console;
+static seg_t membase, memend;
 static char bininit[] = "/bin/init";
 static char binshell[] = "/bin/sh";
 #ifdef CONFIG_SYS_NO_BININIT
@@ -57,6 +59,7 @@ static char *init_command = bininit;
 /*
  * Parse /bootopts startup options
  */
+static char opts;
 static int args = 2;	/* room for argc and av[0] */
 static int envs;
 static int argv_slen;
@@ -82,11 +85,17 @@ static char * INITPROC option(char *s);
 
 static void init_task(void);
 static void INITPROC kernel_banner(seg_t start, seg_t end, seg_t init, seg_t extra);
+static void INITPROC early_kernel_init(void);
 
-
+/* this procedure called using temp stack then switched, no temp vars allowed */
 void start_kernel(void)
 {
-    kernel_init();
+    early_kernel_init();        /* read bootopts using kernel interrupt stack */
+    task = heap_alloc(max_tasks * sizeof(struct task_struct),
+        HEAP_TAG_TASK|HEAP_TAG_CLEAR);
+    if (!task) panic("No task mem");
+    setsp(&task->t_regs.ax);    /* change to idle task stack */
+    kernel_init();              /* continue init running on idle task stack */
 
     /* fork and run procedure init_task() as task #1*/
     kfork_proc(init_task);
@@ -105,25 +114,24 @@ void start_kernel(void)
     }
 }
 
-void INITPROC kernel_init(void)
+static void INITPROC early_kernel_init(void)
 {
-    seg_t base, end;
-
-    /* sched_init sets us (the current stack) to be idle task #0*/
-    sched_init();
-    setup_arch(&base, &end);
-    mm_init(base, end);
-    irq_init();
-    tty_init();
-
+    setup_arch(&membase, &memend);  /* initializes kernel heap */
+    mm_init(membase, memend);       /* parse_options may call seg_add */
+    tty_init();                     /* parse_options may call rs_setbaud */
 #ifdef CONFIG_TIME_TZ
-    tz_init(CONFIG_TIME_TZ);
+    tz_init(CONFIG_TIME_TZ);        /* parse_options may call tz_init */
 #endif
-
 #ifdef CONFIG_BOOTOPTS
-    /* parse options found in /bootops */
-    int opts = parse_options();
+    opts = parse_options();         /* parse options found in /bootops */
 #endif
+}
+
+void INITPROC kernel_init(void)
+{
+    /* set us (the current stack) to be idle task #0*/
+    sched_init();
+    irq_init();
 
     /* set console from /bootopts console= or 0=default*/
     set_console(boot_console);
@@ -163,7 +171,7 @@ void INITPROC kernel_init(void)
     seg_t s = 0, e = 0;
 #endif
 
-    kernel_banner(base, end, s, e - s);
+    kernel_banner(membase, memend, s, e - s);
 }
 
 static void INITPROC kernel_banner(seg_t start, seg_t end, seg_t init, seg_t extra)
@@ -481,6 +489,10 @@ static int INITPROC parse_options(void)
 			nr_map_bufs = (int)simple_strtol(line+6, 10);
 			continue;
 		}
+		if (!strncmp(line,"task=",5)) {
+			max_tasks = (int)simple_strtol(line+5, 10);
+			continue;
+		}
 		if (!strncmp(line,"comirq=",7)) {
 			comirq(line+7);
 			continue;

elks/kernel/exit.c

@@ -9,9 +9,6 @@
 #include <linuxmt/mm.h>
 #include <linuxmt/debug.h>
 
-extern int task_slots_unused;
-extern struct task_struct *next_task_slot;
-
 static void reparent_children(void)
 {
     register struct task_struct *p;

elks/kernel/fork.c

@@ -8,8 +8,8 @@
 
 #include <arch/segment.h>
 
-int task_slots_unused = MAX_TASKS;
-struct task_struct *next_task_slot = task;
+int task_slots_unused;
+__task *next_task_slot;
 pid_t last_pid = -1;
 
 static pid_t get_pid(void)
@@ -27,7 +27,7 @@ static pid_t get_pid(void)
                 last_pid = 1;
             p = &task[0];
         }
-    } while (++p < &task[MAX_TASKS]);
+    } while (++p < &task[max_tasks]);
     return last_pid;
 }
 
@@ -46,7 +46,7 @@ struct task_struct *find_empty_process(void)
     }
     t = next_task_slot;
     while (t->state != TASK_UNUSED) {
-        if (++t >= &task[MAX_TASKS])
+        if (++t >= &task[max_tasks])
             t = &task[1];
     }
     next_task_slot = t;

elks/kernel/sched.c

@@ -17,9 +17,10 @@
 
 #define idle_task task[0]
 
-__task task[MAX_TASKS];
-__ptask current = task;
+__task *task;           /* dynamically allocated task array */
+__ptask current;
 __ptask previous;
+int max_tasks = MAX_TASKS;
 
 extern int intr_count;
 
@@ -192,15 +193,18 @@ void do_timer(void)
 
 void INITPROC sched_init(void)
 {
-    register struct task_struct *t = &task[MAX_TASKS];
+    struct task_struct *t = &task[max_tasks];
 
 /*
- *  Mark tasks 0-(MAX_TASKS-1) as not in use.
+ *  Mark tasks 0-(max_tasks-1) as not in use.
  */
     do {
         (--t)->state = TASK_UNUSED;
     } while (t > task);
 
+    current = task;
+    next_task_slot = task;
+    task_slots_unused = max_tasks;
 /*
  *  Now create task 0 to be ourself.
  */

elkscmd/rootfs_template/bootopts

@@ -1,5 +1,5 @@
 ## boot opts max 511 bytes
-#console=ttyS0,57600 debug net=ne0 3 # sercon+multiuser+net
+#console=ttyS0,57600 debug net=ne0 3 # sercon+muser+net
 #QEMU=1			# QEMU ftp/ftpd
 #TZ=MDT7
 #LOCALIP=10.0.2.16
@@ -12,8 +12,9 @@ wd0=10,0x300,0xCC00,0x80
 #cache=4
 #xmsbuf=2975
 #umb=0xC000:0x800,0xD000:0x1000
+#task=20
 #sync=30		# autosync secs
-#init=/bin/init 3 n	# multiuser serial no rc.sys
+#init=/bin/init 3 n	# muser serial no rc.sys
 #init=/bin/sh		# singleuser sh
 #root=hda1 ro		# root hd partition 1 read-only
 #kstack