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Write an OS for PocketPc
Posted: Sun May 18, 2008 7:17 am
by Karlosoft
It's a few of time that i've a question.
Is possible, write an OS for pocketpc?
Posted: Sun May 18, 2008 8:52 am
by Dex
Yes, but it depends what processor it uses, as to how you go about it.
If its a ARM, let me know as i have done some ARM programming.
Posted: Sun May 18, 2008 9:15 am
by Karlosoft
Yes it's a ARM, i think. On the screen is written that it's a Intel PXA255...
Posted: Sun May 18, 2008 10:21 am
by Dex
Right you need to get a suitable bootload eg: ArmBoot
http://armboot.sourceforge.net/
Also find linux example and google for info, if you get stuck just ask
Download & links
http://hw-server.com/hw_products/sld_hws.html
Intel PXA255 DIMM PC board - a detailed datasheet
http://hw-server.com/files/priloha/dimm_pc.pdf
Primary source about ARM architekture:
www.arm.com.
Arm Reference Manual:
www.arm.com/ARM.
Sources and manuals for gcc, gdb, glib+ and binary utilities :
www.gnu.org.
Kernel souces and patches are on the page:
www.arm.linux.org.uk.
Posted: Sun May 18, 2008 12:21 pm
by Karlosoft
thank you very much
Posted: Sun May 18, 2008 1:36 pm
by Dex
Karlosoft wrote:thank you very much
Your welcome, for my ARM Dev work, i use FasmArm
http://arm.flatassembler.net/
Posted: Sun May 18, 2008 5:02 pm
by pcmattman
You can also compile a GCC toolchain that targets ARM (arm-elf, for instance), but that doesn't replace knowing the assembly
.
It's always nice to be able to code in C instead of assembly though.
Posted: Sun May 18, 2008 7:53 pm
by molux
Hello,
Do you have an idée to emulate a minimliste PocketPC plateform ?
Does i simply have to find an ARM emulator ?
Is there a complicated boot procedure ? (differt thant conventional ARM emulator ?)
An more important, How about the bios ?
(Or where to find documentation for an ipaq for exemple)
Thanks a lot for your response
(Thousand excuses for my bad english)
Molux
Posted: Mon May 19, 2008 4:32 am
by tsp
pcmattman wrote:You can also compile a GCC toolchain that targets ARM (arm-elf, for instance)
Yes,
WinARM is the one I'm using although there are other options also.
Posted: Mon May 19, 2008 5:02 am
by Karlosoft
What are the "elf executable at 0"???
Posted: Mon May 19, 2008 5:03 am
by JamesM
Karlosoft wrote:What are the "elf executable at 0"???
Can you give us some context?
Posted: Mon May 19, 2008 5:07 am
by Karlosoft
yes a moment...
here you are...
Code: Select all
format ELF dwarf executable at 0
entry start
section 'one' executable readable writeable align 020h
start: mov r1,string_hello
mov r0,4 ;SYS_WRITE0
swi 0x123456 ;Multi-ICE DCC semihosting
mov r0,18h ;angel_SWIreason_ReportException
mov r1,20000h ;Software reason code
orr r1,r1,26h ;ADP_Stopped_ApplicationExit
swi 0x123456 ;Multi-ICE DCC semihosting
string_hello db 'Hello ARM semi-hosting world',13,10,0
and thann
Code: Select all
format ELF executable
entry start
segment readable executable
start: mov r0,0
add r1,pc,hello-$-8
mov r2,hello_len
swi 0x900004
mov r0,6
swi 0x900001
hello: db 'Hello world',10
hello_len=$-hello
;dummy section for bss, see http://board.flatassembler.net/topic.php?t=3689
segment writeable
Posted: Mon May 19, 2008 5:44 am
by molux
Hello,
And what about Pocket PC emulation and Pocket PC bios ?
(Does the ARM bios are "standardized" or there is a spécial bios on Pocket pc ?)
thanks in advance
Molux
Posted: Mon May 19, 2008 5:48 am
by Karlosoft
Posted: Mon May 19, 2008 10:09 am
by Dex
The posted programs seem to be examples for running on a OS, maybe linux on the ARM .
To write a OS for a ARM is a lot simpler than the x86, but you need to do most of the work your self, eg: No BIOS to set things up for you.
And most things that need setting up are differant on the differant ARM chips.
But this is a helloworld! bootloader that would work on all ARM chips
Code: Select all
:****************************************;
; ARM BootLoader. ;
;----------------------------------------;
; Prog by Dex. ;
; Coded with FasmARM. ;
; Part of the the x86 to ARM DexOS port. ;
; C:\fasmarm ArmBoot.asm ArmBoot.bin ;
; ;
; C Bamford.2006(c) ;
;****************************************;
format binary
org 0 ; code starts at offset 0.
use32 ; use 32-bit code.
b reset ; b lable (is the same as jmp lable in x86 asm )
b undefined_instruction
b software_interrupt
b prefetch_abort
b data_abort
b not_used
b irq
b fiq
align 4
;********************************;
; boot start. ;
;********************************;
reset:
; here is where your start up code would go.
LetsLoop:
b LetsLoop
;********************************;
; just Loop For Now ;) ;
;********************************;
undefined_instruction:
software_interrupt:
prefetch_abort:
data_abort:
not_used:
irq:
fiq:
LetsLoopForNow:
b LetsLoopForNow
So for example the software int code would be placed under the lable
"software_interrupt" and so on, all that happans when you turn the device on is 4k of code is load from rom to ram starting at 0 and than it jumps to the 0 address.
I may write a tut if i get time.