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* vi: ft=markdown
Welcome to FoolOS
=================
Copyright M.Idziorek 2014 <m.i@gmx.at>
Disclaimer
----------
This is a simple and useless "operating system", with no features,
sorry. Currently it is just the rotting fruit of my explorations of
the 32-bit protected mode and interrupt handling
NOTES
=====
cli; disable interrupts
lgdt
lidt
sti; enable interrupts
Linux Startup x86
=================
1. arch/x86/boot/header.S
Contains the header and linux 16 bit code.
This code should be entered with a bootloader at the address specified
within the header (as _start) which will put us at 'start_of_setup'
Direct loading will put us at 'start2' at the very start which will
show an error message
If everyhing goes right we will enter the 16-bit real mode C module
with:
call main ; should not return
2. arch/x86/boot/main.c
void main(void) will do some checks and detections (cpu,mem,..) and
invoke: go_to_protected_mode();
3. arch/x86/boot/pm.c
go_to_protected_mode() - will disable interrupts and set up the initial
idt and gdt descriptor tables before calling: protected_mode_jump() and
passing the address of code32_start.
4. arch/x86/boot/pmjump.S
back in assembly-world the actual transition is made inside
'protected_mode_jump' and we move on to 'in_pm32' where the data segment
is set up and we jmpl to the 32-bit entry point of the kernel.
5. arch/x86/kernel/head32.c (assumption!?)
void i386_start_kernel(void)
6. init/main.c
start_kernel(void)
setup_arch()!!
Interrupts
==========
arch/x86/include/asm/irq_vectors.h each entry is 8 bytes
ISA interrupts:
0x30 0x0000 0x0000 0x0000 0x0000
0x31
0x32
..
0x3f
TODOS
=====
* study LINUX KERNEL
* GNU HURD
* MINIX
* FreeBSD etc.
NETWORK
=======
look at following linux drivers:
* e1000
notes
=====
* posix - minimal set of function calls!
* distributed os
* caches L1,L2,L3
* controller -> ide inteface of device
* probe memory!
* a20~ wrap
* ssd card reader
* cobol fortran algol? compilers?
* quotation: ontogeny nrecapitulates phylogeny
* own simple sell
check:
apertium?
clang
freebsd
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