Merge commit 'origin/master' into page

1 files changed, 36 insertions, 23 deletions

diff --git a/main.c b/main.c
index 878ea36..a27c4ff 100644
--- a/main.c
+++ b/main.c
@@ -7,40 +7,45 @@
 
 static void bootothers(void);
 static void mpmain(void);
-void jkstack(void)  __attribute__((noreturn));
+void jmpkstack(void)  __attribute__((noreturn));
 void mainc(void);
 
 // Bootstrap processor starts running C code here.
+// Allocate a real stack and switch to it, first
+// doing some setup required for memory allocator to work.
 int
 main(void)
 {
   mpinit();        // collect info about this machine
   lapicinit(mpbcpu());
-  ksegment();      // set up segments
-  picinit();       // interrupt controller
-  ioapicinit();    // another interrupt controller
-  consoleinit();   // I/O devices & their interrupts
-  uartinit();      // serial port
-  pminit();        // discover how much memory there is
-  jkstack();       // call mainc() on a properly-allocated stack 
+  seginit();       // set up segments
+  kinit();         // initialize memory allocator
+  jmpkstack();     // call mainc() on a properly-allocated stack 
 }
 
 void
-jkstack(void)
+jmpkstack(void)
 {
-  char *kstack = kalloc();
-  if (!kstack)
-    panic("jkstack\n");
-  char *top = kstack + PGSIZE;
-  asm volatile("movl %0,%%esp" : : "r" (top));
-  asm volatile("call mainc");
-  panic("jkstack");
+  char *kstack, *top;
+  
+  kstack = kalloc();
+  if(kstack == 0)
+    panic("jmpkstack kalloc");
+  top = kstack + PGSIZE;
+  asm volatile("movl %0,%%esp; call mainc" : : "r" (top));
+  panic("jmpkstack");
 }
 
+// Set up hardware and software.
+// Runs only on the boostrap processor.
 void
 mainc(void)
 {
   cprintf("\ncpu%d: starting xv6\n\n", cpu->id);
+  picinit();       // interrupt controller
+  ioapicinit();    // another interrupt controller
+  consoleinit();   // I/O devices & their interrupts
+  uartinit();      // serial port
   kvmalloc();      // initialize the kernel page table
   pinit();         // process table
   tvinit();        // trap vectors
@@ -63,17 +68,18 @@ mainc(void)
 static void
 mpmain(void)
 {
-  if(cpunum() != mpbcpu()) {
-    ksegment();
+  if(cpunum() != mpbcpu()){
+    seginit();
     lapicinit(cpunum());
   }
   vmenable();        // turn on paging
   cprintf("cpu%d: starting\n", cpu->id);
   idtinit();       // load idt register
-  xchg(&cpu->booted, 1);
+  xchg(&cpu->booted, 1); // tell bootothers() we're up
   scheduler();     // start running processes
 }
 
+// Start the non-boot processors.
 static void
 bootothers(void)
 {
@@ -82,19 +88,23 @@ bootothers(void)
   struct cpu *c;
   char *stack;
 
-  // Write bootstrap code to unused memory at 0x7000.  The linker has
-  // placed the start of bootother.S there.
-  code = (uchar *) 0x7000;
+  // Write bootstrap code to unused memory at 0x7000.
+  // The linker has placed the image of bootother.S in
+  // _binary_bootother_start.
+  code = (uchar*)0x7000;
   memmove(code, _binary_bootother_start, (uint)_binary_bootother_size);
 
   for(c = cpus; c < cpus+ncpu; c++){
     if(c == cpus+cpunum())  // We've started already.
       continue;
 
-    // Fill in %esp, %eip and start code on cpu.
+    // Tell bootother.S what stack to use and the address of mpmain;
+    // it expects to find these two addresses stored just before
+    // its first instruction.
     stack = kalloc();
     *(void**)(code-4) = stack + KSTACKSIZE;
     *(void**)(code-8) = mpmain;
+
     lapicstartap(c->id, (uint)code);
 
     // Wait for cpu to finish mpmain()
@@ -103,3 +113,6 @@ bootothers(void)
   }
 }
 
+//PAGEBREAK!
+// Blank page.
+