change some comments, maybe more informative

delete most comments from bootother.S (since copy of bootasm.S)
ksegment() -> seginit()
move more stuff from main() to mainc()

1 files changed, 32 insertions, 43 deletions

diff --git a/bootother.S b/bootother.S
index 899669a..186873e 100644
--- a/bootother.S
+++ b/bootother.S
@@ -9,80 +9,69 @@
 # Because this code sets DS to zero, it must sit
 # at an address in the low 2^16 bytes.
 #
-# Bootothers (in main.c) sends the STARTUPs, one at a time.
-# It puts this code (start) at 0x7000.
-# It puts the correct %esp in start-4,
-# and the place to jump to in start-8.
+# Bootothers (in main.c) sends the STARTUPs one at a time.
+# It copies this code (start) at 0x7000.
+# It puts the address of a newly allocated per-core stack in start-4,
+# and the address of the place to jump to (mpmain) in start-8.
 #
 # This code is identical to bootasm.S except:
 #   - it does not need to enable A20
 #   - it uses the address at start-4 for the %esp
 #   - it jumps to the address at start-8 instead of calling bootmain
 
-#define SEG_KCODE 1  // kernel code
-#define SEG_KDATA 2  // kernel data+stack
+#define SEG_KCODE 1
+#define SEG_KDATA 2
 
-#define CR0_PE    1  // protected mode enable bit
+#define CR0_PE    1
 
-.code16                       # Assemble for 16-bit mode
+.code16           
 .globl start
 start:
-  cli                         # Disable interrupts
+  cli            
 
-  # Set up the important data segment registers (DS, ES, SS).
-  xorw    %ax,%ax             # Segment number zero
-  movw    %ax,%ds             # -> Data Segment
-  movw    %ax,%es             # -> Extra Segment
-  movw    %ax,%ss             # -> Stack Segment
+  xorw    %ax,%ax
+  movw    %ax,%ds
+  movw    %ax,%es
+  movw    %ax,%ss
 
 //PAGEBREAK!
-  # Switch from real to protected mode, using a bootstrap GDT
-  # and segment translation that makes virtual addresses 
-  # identical to physical addresses, so that the 
-  # effective memory map does not change during the switch.
   lgdt    gdtdesc
   movl    %cr0, %eax
   orl     $CR0_PE, %eax
   movl    %eax, %cr0
 
-  # This ljmp is how you load the CS (Code Segment) register.
-  # SEG_ASM produces segment descriptors with the 32-bit mode
-  # flag set (the D flag), so addresses and word operands will
-  # default to 32 bits after this jump.
   ljmp    $(SEG_KCODE<<3), $start32
 
-.code32                       # Assemble for 32-bit mode
+.code32
 start32:
-  # Set up the protected-mode data segment registers
-  movw    $(SEG_KDATA<<3), %ax    # Our data segment selector
-  movw    %ax, %ds                # -> DS: Data Segment
-  movw    %ax, %es                # -> ES: Extra Segment
-  movw    %ax, %ss                # -> SS: Stack Segment
-  movw    $0, %ax                 # Zero segments not ready for use
-  movw    %ax, %fs                # -> FS
-  movw    %ax, %gs                # -> GS
+  movw    $(SEG_KDATA<<3), %ax
+  movw    %ax, %ds
+  movw    %ax, %es
+  movw    %ax, %ss
+  movw    $0, %ax
+  movw    %ax, %fs
+  movw    %ax, %gs
 
-  # Set up the stack pointer and call into C.
+  # switch to the stack allocated by bootothers()
   movl    start-4, %esp
+
+  # call mpmain()
   call	*(start-8)
 
-  # If the call returns (it shouldn't), trigger a Bochs
-  # breakpoint if running under Bochs, then loop.
-  movw    $0x8a00, %ax            # 0x8a00 -> port 0x8a00
+  movw    $0x8a00, %ax
   movw    %ax, %dx
   outw    %ax, %dx
-  movw    $0x8ae0, %ax            # 0x8ae0 -> port 0x8a00
+  movw    $0x8ae0, %ax
   outw    %ax, %dx
 spin:
   jmp     spin
 
-# Bootstrap GDT
-.p2align 2                                # force 4 byte alignment
+.p2align 2
 gdt:
-  SEG_NULLASM                             # null seg
-  SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff)   # code seg
-  SEG_ASM(STA_W, 0x0, 0xffffffff)         # data seg
+  SEG_NULLASM
+  SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff)
+  SEG_ASM(STA_W, 0x0, 0xffffffff)
 
 gdtdesc:
-  .word   (gdtdesc - gdt - 1)                            # sizeof(gdt) - 1
-  .long   gdt                             # address gdt
+  .word   (gdtdesc - gdt - 1)
+  .long   gdt