Hello Everyone,
I am doing an experiment to emulate x86 real mode in qemu so as to
study assembly programming in GNU assembler. My current status is that
qemu exits with the error:
qemu: fatal: Trying to execute code outside RAM or ROM at 0x000a0000
Please help me get my expt working. Coming to the details, my simple
source files:
startup.S:
======================
.globl start
.text
.code16gcc
start:
jmp main
======================
main.S
======================
.globl main
.text
.code16gcc
main: mov $1, %ax
mov $1, %di
mov $1, %si
mov $1, %dx
cli
hlt
======================
Linker script: As x86 has the hard coded value 0xFFFF0 for the address
of first execution, I am putting my startup script which calls the
main function at 0xFFFF0:
======================
OUTPUT(binary);
ENTRY(start);
SECTIONS
{
.text : { *(.text) }
.data : { *(.data) }
.bss : { *(.bss COMMON) }
. = 0xFFFF0;
.startup . : { startup.o (.text)}
}
=======================
My make output:
===========================
cc -nostdinc -nostdlib -ffreestanding -nostartfiles -nodefaultlibs
-mno-red-zone -c startup.S -o startup.o
cc -nostdinc -nostdlib -ffreestanding -nostartfiles -nodefaultlibs
-mno-red-zone -c main.S -o main.o
ld -T link.ld startup.o main.o -o bin
===========================
Later creating flash image:
========================================
dd if=/dev/zero of=flash.bin bs=4096 count=1024
dd if=bin of=flash.bin bs=4096 conv=notrunc
========================================
And finally starting qemu:
================================
qemu-system-i386 -pflash flash.bin -nographic
=================================
That fails with the error mentioned I already mentioned :
=====================================================
WARNING: Image format was not specified for 'flash.bin' and probing guessed raw.
Automatically detecting the format is dangerous for raw
images, write operations on block 0 will be restricted.
Specify the 'raw' format explicitly to remove the restrictions.
qemu: fatal: Trying to execute code outside RAM or ROM at 0x000a0000
EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000663
ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000
EIP=000afff2 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0000 00000000 0000ffff 00009300
CS =f000 ffff0000 0000ffff 00009b00
SS =0000 00000000 0000ffff 00009300
DS =0000 00000000 0000ffff 00009300
FS =0000 00000000 0000ffff 00009300
GS =0000 00000000 0000ffff 00009300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT= 00000000 0000ffff
IDT= 00000000 0000ffff
CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00000000 CCO=ADDB
EFER=0000000000000000
FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
XMM00=00000000000000000000000000000000 XMM01=00000000000000000000000000000000
XMM02=00000000000000000000000000000000 XMM03=00000000000000000000000000000000
XMM04=00000000000000000000000000000000 XMM05=00000000000000000000000000000000
XMM06=00000000000000000000000000000000 XMM07=00000000000000000000000000000000
=======================================================
Please let me know what I missed.
Thanking in Advance!
Aurabindo
--
Thanks and Regards,
Aurabindo J
