Dear Peter,
Thank you so much for the reply. I have copied the content of the three files I use for the RAM initialization, ram.S, ram.ld and Makefile.
my GCC is: gcc (GCC) 4.6.1 20110908 (Red Hat 4.6.1-9) binutils: Version : 2.21.53.0.2 Vendor: Fedora Project Release : 1.fc17 Build Date: Mon 08 Aug 2011 20:53:40 IRDT
It is compiled for Pentium III, 815/ICH2.
Regards
ram.S ****************************************************** .code16 .section .realmode start: cli mov $0, %ax mov %ax, %ds
#-********************************* #/* Configure the RAM command. */
mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx movw $0x0CFC, %dx in %dx, %eax
and $0x1fffffff, %eax or $0x05000000, %eax
movw $0x0CFC, %dx out %eax, %dx
#;-------------------------------------------------- #general initialization
#50-53************************** mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx mov $0x0cfc, %dx in %dx, %eax
#Res mask and $0x0000F823, %eax
#Bios => cas 2clk or $0x2fcc0140, %eax
mov $0x0cfc, %dx out %eax, %dx
#70,72-73************************** mov $0x0cf8, %dx mov $0x80000070, %eax out %eax, %dx
mov $0x0cfc, %dx movb $0xc0, %al out %al, %dx
mov $0x0cfe, %dx inw %dx, %ax
#Res mask and $0x7704, %ax #Bios or $0x0012, %ax
mov $0x0cfe, %dx out %ax, %dx
#92-93**************************** mov $0x0cf8, %dx mov $0x80000090, %eax out %eax, %dx
mov $0x0cfe, %dx movw $0xff5c, %ax out %ax, %dx
#94-95***************************** mov $0x0cf8, %dx mov $0x80000094, %eax out %eax, %dx
mov $0x0cfe, %dx inw %dx, %ax
#Res mask and $0xffc0, %ax #Bios or $0x001c, %ax
mov $0x0cfe, %dx out %ax, %dx
#98-9B***************************** mov $0x0cf8, %dx mov $0x80000098, %eax out %eax, %dx
movw $0x0cfc, %dx in %dx, %eax
#Res mask and $0x7F887F88, %eax #Bios or $0x80238023, %eax
movw $0x0cfc, %dx out %eax, %dx
#9c-9f*************************** mov $0x0cf8, %dx mov $0x8000009c, %eax out %eax, %dx movw $0x0CFC, %dx in %dx, %eax
#Res mask and $0xFFFF7FFF, %eax #Bios or $0x00008000, %eax
movw $0x0CFC, %dx out %eax, %dx
#2c-2f*************************** mov $0x0cf8, %dx mov $0x8000002c, %eax out %eax, %dx mov $0x0cfc, %dx mov $0x80271043, %eax out %eax, %dx
#;-------------------------------------------------- #NOP /* 1. Apply NOP. */
#display 1
mov $1, %al out %al, $0x80
#%%%%%%%%%%%%%%%%%%%%
mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx
mov $0x0cfc, %dx in %dx, %eax
#Res mask and $0x0000F823, %eax
#Bios => cas 2clk or $0x8fcc0140, %eax
mov $0x0cfc, %dx out %eax, %dx
#%%%%%%%%%%%%%%%%%%%%%%
mov $0x00000000, %ebx mov (%ebx), %eax /* mov $0x08000000, %ebx mov (%ebx), %eax
mov $0x10000000, %ebx mov (%ebx), %eax
mov $0x18000000, %ebx mov (%ebx), %eax */
#%%%%%%%%%%%%%%%%%%%%%
mov $1, %di delay11r: mov $200000, %ecx delay1r: dec %ecx jnz delay1r dec %di jnz delay11r
#;-------------------------------------------------- #precharge /* 2. Precharge all. Wait tRP. */
#display 2
mov $2, %al out %al, $0x80
#%%%%%%%%%%%%%%%%%%%%%%
mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx
mov $0x0cfc, %dx in %dx, %eax
#Res mask and $0x0000F823, %eax #Bios => cas 2clk or $0xafcc0140, %eax mov $0x0cfc, %dx out %eax, %dx
#%%%%%%%%%%%%%%%%%%%%%%
mov $0x00000000, %ebx mov %ds:(%ebx), %eax /* mov $0x08000000, %ebx mov %ds:(%ebx), %eax
mov $0x10000000, %ebx mov %ds:(%ebx), %eax
mov $0x18000000, %ebx mov %ds:(%ebx), %eax */ #%%%%%%%%%%%%%%%%%%%%%%%
mov $10, %di delay21r: mov $1000, %ecx delay2r: dec %ecx jnz delay2r dec %di jnz delay21r
#;-------------------------------------------------- #CBR cycle /* 3. Perform 8 refresh cycles. Wait tRC each time. */
#display 3
mov $3, %al out %al, $0x80
#%%%%%%%%%%%%%%%%%%%%%%
mov $8, %esi refreshcycler: mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx
mov $0x0cfc, %dx in %dx, %eax
#Res mask and $0x0000F823, %eax
#Bios => cas 2clk or $0xefcc0140, %eax
mov $0x0cfc, %dx out %eax, %dx #%%%%%%%%%%%%%%%%%%%%%%%
mov $0x00000000, %ebx mov %ds:(%ebx), %eax /* mov $0x08000000, %ebx mov %ds:(%ebx), %eax
mov $0x10000000, %ebx mov %ds:(%ebx), %eax
mov $0x18000000, %ebx mov %ds:(%ebx), %eax */ #%%%%%%%%%%%%%%%%%%%%%%%
mov $10, %di delay31r: mov $1000, %ecx delay3r: dec %ecx jnz delay3r dec %di jnz delay31r
dec %esi jnz refreshcycler
#;-------------------------------------------------- #mode register set /* 4. Mode register set. Wait two memory cycles. */
#display 4
mov $4, %al out %al, $0x80
#%%%%%%%%%%%%%%%%%%%%%%%%%
mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx
mov $0x0cfc, %dx in %dx, %eax
#Res mask and $0x0000F823, %eax #Bios => cas 2clk or $0xafcc0140, %eax
mov $0x0cfc, %dx out %eax, %dx
#%%%%%%%%%%%%%%%%%%%%%%%%
#1d0 => 150
mov $0x000001d0, %ebx mov %ds:(%ebx), %eax /* mov $0x08000150, %ebx mov %ds:(%ebx), %eax
mov $0x10000650, %ebx mov %ds:(%ebx), %eax
mov $0x18000650, %esi mov %ds:(%ebx), %eax */ #%%%%%%%%%%%%%%%%%%%%%%%%%%%
mov $10, %di delay41r: mov $1000, %ecx delay4r: dec %ecx jnz delay4r dec %di jnz delay41r
#;-------------------------------------------------- #normal operation /* 5. Normal operation (enables refresh at 15.6usec). */
#display 5
mov $5, %al out %al, $0x80
#%%%%%%%%%%%%%%%%%%%%%%%%%%
mov $0x0cf8, %dx mov $0x80000050, %eax out %eax, %dx mov $0x0cfc, %dx in %dx, %eax
#Res mask and $0x0000F823, %eax #Bios => cas 2clk or $0x2fcc0140, %eax
mov $0x0cfc, %dx out %eax, %dx
#%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
mov $0x00000000, %ebx mov %ds:(%ebx), %eax /* mov $0x08000000, %ebx mov %ds:(%ebx), %eax
mov $0x10000000, %ebx mov %ds:(%ebx), %eax
mov $0x18000000, %ebx mov %ds:(%ebx), %eax */ #%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
mov $10, %di delay51r: mov $1000, %ecx delay5r: dec %ecx jnz delay5r dec %di jnz delay51r
#;-------------------------------------------------- mov $10, %al out %al, $0x80 #;-------------------------------------------------- mov $0xffff, %cx delayea1r: dec %cx jnz delayea1r
#*********************..................**************
#;enabling protected mode
cli
lgdtl %cs:32
mov $0x10, %ax mov %ax, %ds mov %ax, %es mov %ax, %fs mov %ax, %gs mov %ax, %ss
mov $0x34, %al out %al, $0x80
mov %cr0, %eax or $1, %eax mov %eax, %cr0
data32 ljmp $0x0008, $0xfffc0000
.section .gdtsection gdt: .byte 0, 0, 0, 0, 0, 0, 0, 0 .byte 0xff, 0xff, 0, 0, 0, 0x9a, 0xdf, 0 .byte 0xff, 0xff, 0, 0, 0, 0x92, 0xdf, 0 .byte 0xff, 0xff, 0, 0, 0, 0x92, 0xdf, 0 .byte 32, 0, 0, 0, 0xff, 0xff
.code32 .section .protectedmode protectedmode:
mov $0x42, %al out %al, $0x80
#*********************..................***********************
mov $0xffff, %cx delayea1: dec %cx jnz delayea1
#write
mov $0x8ffff, %ebx mov $0x59, %al mov %al, (%ebx)
#read
mov $0x8ffff, %ebx mov (%ebx), %al outb %al, $0x80
#*********************..................**************
end: jmp end
.code16 .section .reset jmp start
ram.ld ***************************************************** SECTIONS { /DISCARD/ : { *(.comment) *(.note.*) *(.note) } }
SECTIONS { . = 0xfffc0000; .text : { compstart = .; *(.protectedmode); . = compstart + 0x30000; compstart = .; *(.gdtsection); . = compstart + 0x8200; compstart = .; *(.realmode); . = compstart + 0x7df0; compstart = .; *(.reset); . = compstart + 0x10; }
}
Makefile **************************************************** all: as -march=pentiumiii -mtune=pentiumiii -o ram.o ram.S ld ram.o -o ram -T ram.ld objcopy -O binary ram ram.img
****************************************************
On Wed, Nov 30, 2011 at 12:57 PM, Peter Stuge peter@stuge.se wrote:
ali hagigat wrote:
I am working with Pentium III, Intel GMCH, 82815 and Intel ICH2, 82801.
I managed to initialize DRAM controller to recognize the first 640 K of the memory correctly in the real mode.
When i switch to the protected mode, CPU writes to the first 64K only. Every other read/write from the higher addresses leads to CPU restart.
Can anybody say what is going on?
Not unless you show your code.
One explanation would be that you haven't done a proper switch into protected mode (setting up a descriptor table and initializing selectors) which would make the CPU triple fault and reset on accesses outside whatever the descriptors happen to be. If this is the case, I think that Intel's IA-32 architecture manuals have good info on what you need to do, and of course you can study both coreboot sources as well as some good old DOS extenders such as Tran's PMODE32, DOS4GW from Watcom or my personal favorite DOS32.
//Peter
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