Numerous changes including the following:

  + DEBUG_EARLY_START re-added (Eric Valette)
  + segment register initialization (Aleksey/Quality Quorum)
  + heap size use correction
  + more debug printk's
  + increased heap size.

Now works with grub boot on all systems I have access to including
desktops and a laptop.  This is with the i386-rtems tools.
Neither i386-rtemself nor netboot produces a working executable.

1 files changed, 46 insertions, 207 deletions

diff --git a/c/src/lib/libbsp/i386/pc386/start/start.s b/c/src/lib/libbsp/i386/pc386/start/start.s
index 3ed542c255..8be3defef4 100644
--- a/c/src/lib/libbsp/i386/pc386/start/start.s
+++ b/c/src/lib/libbsp/i386/pc386/start/start.s
@@ -12,10 +12,8 @@
 |
 | Instituto Superior Tecnico * Lisboa * PORTUGAL
 +--------------------------------------------------------------------------+
-|
 | Modified the 20/05/1998  by valette@crf.canon.fr in order to give a working
 | example of eraly stage debugging via the DEBUG_EARLY_START define.
-|
 +--------------------------------------------------------------------------+
 | Disclaimer:
 |
@@ -38,22 +36,19 @@
 |  $Id$
 +--------------------------------------------------------------------------*/
 
+/*
+ * The most trivial start.s possible. It does not know anything
+ * about system it is running on, so it will jump to appropriate
+ * place in BSP specific place to do things it knows nothing about
+ */
 
 #include "asm.h"
 
 /*----------------------------------------------------------------------------+
-| A Descriptor table register has the following format:	
-+----------------------------------------------------------------------------*/
-
-.set DTR_LIMIT, 0		# offset of two byte limit
-.set DTR_BASE,  2		# offset of four byte base address
-.set DTR_SIZE,  6		# size of DTR register
-
-/*----------------------------------------------------------------------------+
 | Size of heap and stack:	
 +----------------------------------------------------------------------------*/
 
-.set HEAP_SIZE,  0x2000
+.set HEAP_SIZE,  256
 .set STACK_SIZE, 0x1000
 
 /*----------------------------------------------------------------------------+
@@ -65,20 +60,19 @@ BEGIN_CODE
 	PUBLIC (start)		# GNU default entry point
 
 	EXTERN (boot_card)
-	EXTERN (load_segments)
-	EXTERN (exit)
+	EXTERN (_load_segments)
+	EXTERN (_return_to_monitor)
 	EXTERN (_IBMPC_initVideo)
-	EXTERN (debugPoolingGetChar)
+	EXTERN (debugPollingGetChar)
 
 /*
- * In case it crash on your machine and this is not due
+ * In case this crashes on your machine and this is not due
  * to video mode set by the loader, you may try to define
- * the follwoing variable
-#define DEBUG_EARLY_START
+ * the following variable:
  */
-	
-SYM (start):
+#define DEBUG_EARLY_START
 
+SYM (start):
         nop
         cli			# DISABLE INTERRUPTS!!!
 #ifdef DEBUG_EARLY_START
@@ -98,12 +92,13 @@ SYM (start):
 	call	printk
 	addl	$4, esp
 
-	call	debugPoolingGetChar
+	/*call	debugPollingGetChar */
 #endif	
 
 /*----------------------------------------------------------------------------+
 | Load the segment registers (this is done by the board's BSP) and perform any
-| other board specific initialization procedures. 
+| other board specific initialization procedures, this piece of code
+| does not know anything about 
 |
 | NOTE: Upon return, gs will contain the segment descriptor for a segment which
 |       maps directly to all of physical memory.
@@ -119,8 +114,7 @@ SYM (start):
 SYM (_establish_stack):
 
 	movl	$_end, eax		# eax = end of bss/start of heap
-	addl	$HEAP_SIZE, eax		# eax = end of heap
-	movl	eax, stack_start	# Save for brk() routine
+	addl	_heap_size, eax		# eax = end of heap
 	addl	$STACK_SIZE, eax	# make room for stack
 	andl	$0xffffffc0, eax	# align it on 16 byte boundary
 	movl	eax, esp		# set stack pointer
@@ -141,112 +135,18 @@ SYM (zero_bss):
 	repne				# while ecx != 0
 	stosl				#   clear a long in the bss
 
-	/*---------------------------------------------------------------------+
-	| Copy the Global Descriptor Table to our space
-	+---------------------------------------------------------------------*/
-
-	sgdt	SYM (_Original_GDTR)	# save original GDT
-	movzwl	SYM (_Original_GDTR)+DTR_LIMIT, ecx	# size of GDT in bytes;
-					# limit is 8192 entries * 8 bytes per
-
-	/*---------------------------------------------------------------------+
-	| make ds:esi point to the original GDT
-	+---------------------------------------------------------------------*/
-
-	movl	SYM (_Original_GDTR)+DTR_BASE, esi
-	push	ds			# save ds
-	movw	gs, ax
-	movw	ax, ds
-
-	/*---------------------------------------------------------------------+
-	| make es:edi point to the new (our copy) GDT
-	+---------------------------------------------------------------------*/
-
-	movl	$ SYM (_Global_descriptor_table), edi
-
-	rep
-	movsb				# copy the GDT (ds:esi -> es:edi)
-
-	pop	ds			# restore ds
-
-	/*---------------------------------------------------------------------+
-	| Build and load new contents of GDTR
-	+---------------------------------------------------------------------*/
-
-	movw	SYM (_Original_GDTR)+DTR_LIMIT, ecx	# set new limit
-	movw	cx, SYM (_New_GDTR)+DTR_LIMIT
-
-	push	$ SYM (_Global_descriptor_table)
-	push	es
-	call	SYM (i386_Logical_to_physical)
-	addl	$6, esp
-	movl	eax, SYM (_New_GDTR)+DTR_BASE	# set new base
-
-	cmpb	$0, SYM (_Do_Load_GDT)	# Should the new GDT be loaded?
-	je	SYM (no_gdt_load)	# NO, then branch
-	lgdt	SYM (_New_GDTR)		# load the new GDT
-
-SYM (no_gdt_load):
-
-	/*---------------------------------------------------------------------+
-	| Copy the Interrupt Descriptor Table to our space
-	+---------------------------------------------------------------------*/
-
-	sidt	SYM (_Original_IDTR)	# save original IDT
-	movzwl	SYM (_Original_IDTR)+DTR_LIMIT, ecx	# size of IDT in bytes;
-					#limit is 256 entries * 8 bytes per
-
-	/*---------------------------------------------------------------------+
-	| make ds:esi point to the original IDT
-	+---------------------------------------------------------------------*/
-
-	movl	SYM (_Original_IDTR)+DTR_BASE, esi
-
-	push	ds			# save ds
-	movw	gs, ax
-	movw	ax, ds
-
-	/*---------------------------------------------------------------------+
-	| make es:edi point to the new (our copy) IDT
-	+---------------------------------------------------------------------*/
-
-	movl	$ SYM (Interrupt_descriptor_table), edi
-
-	rep
-	movsb				# copy the IDT (ds:esi -> es:edi)
-	pop	ds			# restore ds
-
-	/*---------------------------------------------------------------------+
-	| Build and load new contents of IDTR
-	+---------------------------------------------------------------------*/
-
-	movw	SYM (_Original_IDTR+DTR_LIMIT), ecx	# set new limit
-	movw	cx, SYM (_New_IDTR)+DTR_LIMIT
-
-	push	$ SYM (Interrupt_descriptor_table)
-	push	es
-	call	SYM (i386_Logical_to_physical)
-	addl	$6, esp
-	movl	eax, SYM (_New_IDTR)+DTR_BASE		# set new base
-
-	cmpb	$0, SYM (_Do_Load_IDT)	# Should the new IDT be loaded?
-	je	SYM (no_idt_load)	# NO, then branch
-	lidt	SYM (_New_IDTR)		# load the new IDT
-
-SYM (no_idt_load):
-
-	/*---------------------------------------------------------------------+
-	| Initialize the i387.
-	|
-	| Using the NO WAIT form of the instruction insures that if it is not
-	| present the board will not lock up or get an exception.
-	+---------------------------------------------------------------------*/
+/*---------------------------------------------------------------------+
+| Initialize the i387.
+|
+| Using the NO WAIT form of the instruction insures that if it is not
+| present the board will not lock up or get an exception.
++---------------------------------------------------------------------*/
 
 	fninit				# MUST USE NO-WAIT FORM
 
-	/*---------------------------------------------------------------------+
-	| Transfer control to User's Board Support Package
-	+---------------------------------------------------------------------*/
+/*---------------------------------------------------------------------+
+| Transfer control to User's Board Support Package
++---------------------------------------------------------------------*/
 
 	pushl	$0			# environp
 	pushl	$0			# argv
@@ -254,106 +154,45 @@ SYM (no_idt_load):
 	call	SYM (boot_card)
 	addl	$12, esp
 
-	/*---------------------------------------------------------------------+
-	| Clean up
-	+---------------------------------------------------------------------*/
-
-	EXTERN (return_to_monitor)
-
-	PUBLIC (Bsp_cleanup)
-
-SYM (Bsp_cleanup):
-
-	cmpb	$0, SYM (_Do_Load_IDT)	# Was the new IDT loaded?
-	je	SYM (no_idt_restore)	# NO, then branch
-	lidt	SYM (_Original_IDTR)	# restore the new IDT
-
-SYM (no_idt_restore):
-
-	cmpb	$0, SYM (_Do_Load_GDT)	# Was the new GDT loaded?
-	je	SYM (no_gdt_restore)	# NO, then branch
-	lgdt    SYM (_Original_GDTR)	# restore the new GDT
-
-SYM (no_gdt_restore):
+/*---------------------------------------------------------------------+
+| Clean up - we do not know anything about it, so we will
+| jump to BSP specific code to do cleanup
++---------------------------------------------------------------------*/
 
 	jmp	SYM (_return_to_monitor)
 
 END_CODE
 
-/*----------------------------------------------------------------------------+
-| DATA section
-+----------------------------------------------------------------------------*/
-
 BEGIN_DATA
 
-	EXTERN (Do_Load_IDT)	# defined in the BSP
-	EXTERN (Do_Load_GDT)	# defined in the BSP
-
-	.align	2
-	PUBLIC (start_frame)
-SYM (start_frame):
-	.long	0
+	PUBLIC(_heap_size)
+SYM(_heap_size):
+	.long HEAP_SIZE << 10
 
-	PUBLIC (stack_start)
-SYM (stack_start):
-	.long	0
+	PUBLIC(_stack_size)
+SYM(_stack_size):
+	.long STACK_SIZE
 
 #ifdef DEBUG_EARLY_START
-	
+
 	PUBLIC (welcome_msg)
 SYM (welcome_msg) :
 	.string "Ready to debug RTEMS ?\nEnter <CR>\n"
 
-#endif
-		
-END_DATA
-
-/*----------------------------------------------------------------------------+
-| BSS section
-+----------------------------------------------------------------------------*/
-
-BEGIN_BSS
-
-	PUBLIC (_heap_size)
-SYM (_heap_size):
-	.long	HEAP_SIZE
-
-	PUBLIC (_stack_size)
-SYM (_stack_size):
-	.long	STACK_SIZE
-
-	PUBLIC (Interrupt_descriptor_table)
-SYM (Interrupt_descriptor_table):
-	.space (256 * 8)	# reserve space for all 256 interrupts
+	PUBLIC (hex_msg)
+SYM (hex_msg) :
+	.string "0x%x\n"
 
-	PUBLIC (_Original_IDTR)
-SYM (_Original_IDTR):
-	.space DTR_SIZE
+	PUBLIC (made_it_msg)
+SYM (made_it_msg) :
+	.string "made it to %d\n"
 
-	PUBLIC (_New_IDTR)
-SYM (_New_IDTR):
-	.space DTR_SIZE
+#endif
 
-	PUBLIC (_Global_descriptor_table)
-SYM (_Global_descriptor_table):
-	.space (3 * 8)	# the PC386 bsp only needs 3 segment descriptors:
-			#   NULL, CODE and DATA
-	PUBLIC (_Original_GDTR)
-SYM (_Original_GDTR):
-	.space DTR_SIZE
+END_DATA
 
-	PUBLIC (_New_GDTR)
-SYM (_New_GDTR):
-	.space DTR_SIZE
+END
 
-	PUBLIC (_Physical_base_of_ds)
-SYM (_Physical_base_of_ds):
-	.space 4
 
-	PUBLIC (_Physical_base_of_cs)
-SYM (_Physical_base_of_cs):
-	.space 4
 
-END_BSS
 
-END