Kwaikwayon Linus Torvalds: Createirƙiri tsarin aikinku daga karce (I)

Da farko dai, kuyi tsokaci akan cewa wannan shine labarina na farko kuma ina fatan duk kuna son sa.

A cikin wannan jerin zamuyi koyi Linus Torvalds, zamu kirkiro tsarin aikin mu daga 0. A wannan karon na farko zamu ga tayar kuma zamu sanya rubutu akan allon daga kwayar mu.

A nawa yanayin ana kiran tsarin aiki NextDivel. Shawara ta farko wacce dole ne muyi shawara da zaran munyi la'akari da tsarin aiki shine menene bootloader zai kasance?

Anan akwai bambance-bambancen da yawa, kuma muna iya ƙirƙirar kanmu da kanmu; duk da haka a cikin wannan darasin zan yi amfani da shi GRUB, saboda yawancin sun san abu kaɗan ko kaɗan game da shi. Muna ƙirƙirar babban fayil wanda zai zama tushen tsarin aikinmu kuma a can muka ƙirƙiri / boot / grub babban fayil

mkdir nextroot && cd nextroot

mkdir -p boot/grub

Anan muke ƙirƙirar fayil ɗin grub.cfg kamar haka:

menuentry "NextDivel" {
echo "Booting NextDivel"
multiboot /next/START.ELF
boot
}


A cikin wannan fayil ɗin mun ga yadda GRUB zai loda kwaya, a wannan yanayin, a cikin /next/START.ELF. Yanzu dole ne mu ƙirƙiri kwaya.

Don wannan zamu buƙaci GCC y GAS (mai tattara aikin GNU, yawanci yakan zo tare da gcc). Don haka zamu kirkiro kwaya.

Da farko zamuyi fayil mai suna kernel.asm. Wannan fayil ɗin zai ƙunshi maɓallin farawa na kwaya kuma zai bayyana ma'anar yawa (fasalin wasu bootloaders kamar GRUB). Abun cikin kernel.asm zai zama:

.text
.globl start
start:
jmp multiboot_entry
.align 4
multiboot_header:
.long 0x1BADB002
.long 0x00000003
.long -(0x1BADB002+0x00000003)
multiboot_entry:
movl $(stack + 0x4000), %esp
call NextKernel_Main
loop: hlt
jmp loop
.section ".bss"
.comm stack,0x4000

Duk abin da ya shafi multiboot shine kawai ya bi bayanin ƙayyadadden abu ba ƙari. Komai zai fara a farko, zai kira multiboot_entry, za mu bayyana mahimmin rubutun a farkon 4k kuma za mu sanya shi (tare da movl).

Daga baya zamu kira NextKernel_Main wanda shine aikinmu na kernel C. A cikin madauki muna dakatarwa don dakatar da kwamfutar. Wannan ya tattara tare da:

as -o kernel.o -c kernel.asm

Yanzu za mu shiga shirye-shirye a cikin C. Za ku yi tunanin cewa yanzu komai wani yanki ne na waina, mun sa a bugawa en main kuma shi ke nan, mun yi shi.

To a'a, tunda bugawa y main ayyuka ne waɗanda tsarin aiki ya bayyana su, amma muna ƙirƙirar su! Zamu iya amfani da ayyukan da muka ayyana kanmu kawai.

A cikin surori na gaba zanyi magana game da yadda ake sanya namu ɗakin karatu na C (glibc, bionic, newlibc) amma lokaci zuwa lokaci. Munyi magana cewa muna son sanya rubutu akan allo, da kyau zamu ga yadda zamuyi.

Akwai hanyoyi biyu, daya shine a kira shi BIOS wani kuma shine sarrafa ƙwaƙwalwar allo kai tsaye. Zamuyi na karshen ne saboda yafito fili daga C sannan kuma zai bamu damar yin hakan lokacin da muka shiga yanayin kariya.

Mun ƙirƙiri fayil mai suna NextKernel_Main.c tare da waɗannan abubuwan masu zuwa:

int NextKernel_Main()
{
char *str = "NextDivel says Hello World", *ch;
unsigned short *vidmem = (unsigned short*) 0xb8000;
unsigned i;
for (ch = str, i = 0; *ch; ch++, i++)
vidmem[i] = (unsigned char) *ch | 0x0700;
return 0;
}

Da wannan muke sarrafa ƙwaƙwalwar kai tsaye VGA da halayya ta hali muna rubuta shi. Muna tattarawa ta hanyar kashe stdlib:
gcc -o NextKernel_Main.o -c NextKernel_Main.c -nostdlib -fPIC -ffreestanding

Idan kun sanya shi a yanzu, kuna so ku gwada sabon tsarin aikin ku yanzu, amma ba mu gama ba tukuna. Muna buƙatar ƙaramin fayil wanda zai gaya wa mai tarawa a ina a cikin fayil ɗin ya bar kowane ɓangare. Ana yin wannan tare da rubutun mahaɗi. Mun ƙirƙiri link.ld:

ENTRY(start)
SECTIONS
{
. = 0x00100000;
.multiboot_header :
{
*(.multiboot_header)
}
.text :
{
code = .; _code = .; __code = .;
*(.text)
. = ALIGN(4096);
}
.data :
{
data = .; _data = .; __data = .;
*(.data)
*(.rodata)
. = ALIGN(4096);
}
.bss :
{
bss = .; _bss = .; __bss = .;
*(.bss)
. = ALIGN(4096);
}
end = .; _end = .; __end = .;
}


Da wannan muke ayyana matsayin kowane sashe da mashigar shigowa, farawa, wanda muka bayyana a cikin kernel.asm. Yanzu zamu iya haɗuwa da duk wannan haɗuwa:

gcc -o START.ELF kernel.o NextKernel_Main.o -Tlink.ld -nostdlib -fPIC -ffreestanding -lgcc

Yanzu mun kwafe START.ELF zuwa / gaba a cikin aljihun mu wanda yayi daidai da tushen tsarin aikin mu. Muna tafiya zuwa babban fayil na sabon tsarin aikinmu tare da na'ura mai kwakwalwa tare da tabbatar da cewa akwai fayiloli guda biyu: daya /boot/grub/grub.cfg da wani /next/START.ELF.

Muna zuwa babban kundin adireshi kuma muna kiran mai amfani da kere kere ta ISO tare da GRUB da ake kira girki-mkrescue

grub-mkrescue -o nextdivel.iso nextroot

Da zarar munyi wannan zamu sami ISO. Ana iya buɗe wannan ISO akan kwamfutoci x86 (Ragowar 64 ma) da injunan kama-da-wane. Don gwada shi, zan yi amfani da shi QEMU. Muna kira QEMU daga layin umarni:

qemu-system-i386 nextdivel.iso

Zai fara SeaBIOS kuma daga baya zamu samu GRUB. Nan gaba idan komai yayi daidai zamu ga jimlar mu.
Za kuyi tunanin cewa wannan yana da wahala, na amsa, haka ne.

Haƙiƙa ƙirƙirar tsarin aiki yana da wahala kuma wannan ɗin a nan baya yin komai mai amfani. A cikin surori na gaba zamu ga yadda ake sarrafa launuka akan allon, adana ƙwaƙwalwar ajiya kuma idan zan iya, yadda ake samun bayanai daga maballin.

Idan wani baya son kwafa komai a nan, ina da wurin ajiyewa a GitHub (ƙarin bayani) tare da tsarin aiki NextDivel. Idan kanaso ka tara NextDivel kawai kuna da git da cmake:

git clone https://github.com/AdrianArroyoCalle/next-divel
cd next-divel
mkdir build && cd build
cmake ..
make
make DESTDIR=next install
chmod +x iso.sh
./iso.sh
qemu-system-i386 nextdivel.iso


Ina ƙarfafa ku da ku ba da haɗin kai a kan NextDivel idan kuna da lokaci da sha'awar ƙirƙirar tsarin aiki. Zai yiwu har ma ya fi Linux ... lokaci zai gaya.